{"paper_id":"61e05745-3ffd-41dd-9ddb-1c311b3a949f","body_text":"Traditionally, female reproductive health issues have been underrepresented in research. For example, a 2020 analysis found that there is a significant gender disparity in the allocation of NIH research funding – in nearly 75% of diseases that primarily affect one gender, the funding pattern favors the male-affecting disease. 1  Similar statistics were reported for the preferential funding of prostate cancer research compared with uterine, ovarian, and cervical cancer by the National Cancer Institute. 2  Disparities in funding patterns can lead to disproportionate amounts of research being conducted toward the prevention and treatment of disease, particularly in the realm of exploring new and next-generation classes of medications.\nRecently, mRNA therapies have become widely known from the success of the Moderna and Pfizer/BioNTech COVID-19 vaccines. Beyond application as vaccines against infectious disease, however, mRNA therapies also have applications in protein replacement therapies, immunotherapies, vaccinations, stem cell reprogramming, and other highly impactful applications. 3  Despite this wide array of possibilities, the use of mRNA therapy for female reproductive health remains nascent and is still in the process of being fully realized. Here, we review advances in mRNA therapies through the lens of improving female reproductive health. Specifically, we begin our review by discussing the fundamental structure and biochemical modifications associated with mRNA-based drugs. Then, we discuss various packaging technologies including lipid nanoparticles that can be utilized to protect and transport mRNA drugs to target cells in the body. Last, we conclude our review by discussing the usage of mRNA therapy for addressing pregnancy-related health and vaccination against sexually transmitted diseases in women. In undertaking this review, our aim is to provide a fundamental background understanding of mRNA therapy and its usage to specifically address female health issues, with an overarching goal of providing information toward addressing gender disparity in certain aspects of health research.\n\nRNA is a biological macromolecule that is an integral part of the central dogma of biology. In general, RNA is a biological polymer that consists of repeating units called nucleotides. Nucleotides are the building blocks of all endogenous nucleic acids and consist of three parts: a monomeric sugar, a phosphodiester linkage bond, and a cyclic nitrogenous base. In RNA, the sugar component of each nucleotide is ribose, a five-membered cyclic sugar. The 3-position and 5-position hydroxyl groups of each ribose ring are also involved in a phosphate bond, thereby forming a phosphodiester linkage between consecutive ribose molecules that, in conjunction with the ribose sugars, form the long polymeric chain that scaffolds genetic information. This genetic information is encoded in the pattern of cyclic nitrogenous bases that branch off from the 1-position of the ribose ring. Four bases are commonly found in endogenous RNA: adenine, uracil, guanine, and cytosine. The arrangement of these four bases forms the primary structure of RNA, including all the covalently interacting atoms. These covalent interactions favor the formation of secondary structure elements of RNA, including single and double-stranded helices, hairpin loops, and other local topographies governed by intramolecular forces such as hydrogen bonds. These secondary structures play an essential role in contributing to the tertiary and quaternary structure of RNA molecules. 4  Although there are many types of RNA with a wide variety of important functions including mRNA, siRNA, tRNA, rRNA, dsRNA and miRNA, this review will focus on mRNA therapy within applications for female reproductive health.\nThough mRNA has been studied for several decades, its use as a clinically approved therapy was not widely available until the development of the COVID-19 vaccine. 5  Endogenously, mRNA is synthesized by cells as a transient messenger of information encoded in the DNA, the blueprint for protein synthesis. RNA polymerase proteins copy the information contained in the DNA to an mRNA transcript in the nucleus, which is exported and translated to protein by both ER-associated and free-floating ribosomes. The expression of an mRNA is a crucial step in the production of the protein encoded by its transcript.\nThe successful treatment of disease by mRNA therapy requires the delivery of such mRNA to the target cells at desired doses. As novel mRNA therapies have emerged, barriers to effective delivery have surfaced. Specifically, mRNA can be immunogenic and subsequently cause significant negative side effects. 6  Additionally, mRNA contains a strongly negative overall charge because of the phosphodiester bonds that link each monomer to one another. Finally, mRNA is susceptible to degradation via the nucleases present in the extracellular environment. 7  To overcome these delivery barriers, structural modifications and carrier systems have been employed. 8  Here, we outline these advances, starting with structural modifications of the mRNA itself and then the use of lipid nanoparticles as carriers. Next, we discuss the use of mRNA therapy in pregnancy and sexually transmitted infection (STI) vaccination, with particular emphasis on relevant clinical trials.\nWhile mRNA presents a new and exciting class of drugs, native mRNA may not make an efficacious drug. Toll-like receptors (TLRs) 3, 7, and 8, and cytoplasmic helicases recognize nonself mRNA and raise an immune response to attack such mRNAs. 9 – 12  Additionally, the production of mRNA via classical synthetic chemistry routes may face significant challenges, as mRNA transcripts can be thousands of bases long. Accordingly, bacterial systems are often exploited for in vitro transcription as a means of mRNA production. Here, the structure of endogenous mRNA itself can be modulated to assist in evading the immune system and prevent degradation via extracellular nucleases. The modifications can include substitutions of endogenous nucleic acid monomers for synthetically derived versions with an increased ability to evade the immune cells circulating through the body. Also, substitutions of functional groups within the ribose sugar, phosphodiester backbone, and nitrogenous bases can make mRNAs less susceptible to degradation by nucleases. However, any chemical modifications to the structure of mRNA nucleotides must be able to be recognized and utilized by the bacterial transcription proteins.\nThe combination of modifications that can exist on a single mRNA transcript is nearly endless because of the diversity of substitutions that can be implemented at any of the mRNA monomers across the macromolecule. Alterations to the regions of the mRNA sequence are also common in emerging mRNA therapies. Generally, mRNA transcripts consist of a 5’ cap, a 5’ untranslated region (UTR), an open reading frame (ORF), a 3’ UTR, and a polyadenosine tail. Efforts to optimize mRNA therapies have targeted these regions and the nucleotides themselves ( Figure 1 ). Here, we discuss select sequence and nucleotide modifications that have been proposed for mRNA therapies.\nEukaryotic mRNA sequences begin with a 5’ cap, made of 7-methylguanasine, that is attached to the first nucleotide of the sequence through a triphosphate linkage (m 7 GpppN). This cap regulates mRNA expression by interacting with initiation factors and decapping enzymes that cause degradation. 13  The addition of a 5’ cap in  in vitro  transcription is difficult because bacterial systems do not naturally incorporate this cap. An m 7 GpppG dinucleotide is typically used, but the noneukaryotic system is susceptible to incorporating this cap in the reverse direction – that is, attaching the m 7 G nucleotide where the G nucleotide is meant to go. These reversed caps can cause negative impacts on protein expression. 14\nTo combat this, antireverse cap analogues (ARCAs) have been developed with modifications including deoxygenation and methylation to the 3’ and 2’ positions of the m 7 G moiety to make them inaccessible for ligation to the mRNA and ensure their correct orientation. 15 , 16  Phosphate linkages of mRNA 5’ caps have also been modified. Endogenous mRNA degradation can occur via the cleavage of the phosphate linkage between the last nucleotide and the m 7 G. 17  The incorporation of sulfur in place of nonbridging oxygens to form a phosphorothioate moiety in this phosphate linkage has displayed resistance to degradation and increased expression. 17 , 18  This phenomenon has been linked to the binding affinity of these analogues to the eukaryotic translation initiation factor, eIF4E. 19  Additionally, modifications to the ribose ring of the 5’ cap have also been explored. Isopropylidene conjugations to the 2’ and 3’ positions of the ribose offer greater scalability and more straightforward synthetic routes, though they may demonstrate a significant decrease in protein expression. 20  Alternatively, a trinucleotide cap containing a locked nucleic acid (m7 LNA GpppAmpG) was synthesized and caused a 5 fold increase in translation when compared with the endogenous cap and ARCAs, attributed in part to the selectivity for correct cap direction. 21 , 22  Taken together, these modifications show that incorporating a 5’ cap in the correct orientation may be critical for the expression of therapeutic mRNA because of its interactions with the translation initiation factors and its regulatory role in the mRNA transcript.\nEach mRNA transcript contains UTRs on either side of the ORF. These UTRs have been known to influence the expression of the gene encoded in the mRNA, though the mechanism for this impact is not entirely understood. Indeed, when mRNAs encoding reporter genes were engineered with UTRs from proteins with large half-lives, such as cytochrome B245⍺, the protein expression increased. Interestingly, there was no observed effect on the stability of the RNA transcript itself. 23  The incorporation of UTRs from C3, 24  cytochrome p450E1, 24  β-globin, 25 , 26  mtRNR1, 27  AES, 27  HSD17B4, 28  and PSMB3 28  have also been used to increase protein expression. Overall, optimization of UTRs for protein expression may require optimization for specific cell types and mRNA transcripts. 24 , 27 , 29\nTo streamline the cell specificity and transcript specificity of UTR optimization, some short and “minimalistic” UTRs have been developed, containing less than 20 nucleotides and including only the essential translation initiators. These UTRs have shown improved protein expression for multiple reporter genes in both in vitro and in vivo models by using only the minimum required nucleotides to avoid interactions with immunogenic and inhibitory molecules. 30  Another study incorporated phosphorothioate moieties into the phosphodiester bond connecting nucleotides throughout the mRNA transcript. They found that phosphorothioate in the 5’ UTR of various proteins exhibited an increase in the expression of the protein, likely due to increased interaction with the initiation machinery. 31  As the function of UTRs is not fully understood, the optimization of their modulation is very complex and will likely be different across cell types and mRNA transcripts.\nThe open reading frame (ORF) is the portion of the mRNA transcript that contains the codons that are translated into amino acids and proteins. Modifications within this sequence must be very precise so as to not disrupt the process of translation.\nMany of the modifications to mRNA nucleotides involve the modulation of uridine. Pseudouridine is a natural isomer of uridine, and its incorporation into mRNA has increased the stability of the mRNA transcript as well as protein expression. 32 – 37  Other modifications including 5-methoxyuridine, 35 , 36 , 38 , 39  thiouridine, 36 , 38 , 40  and methylpseudouridine 35 , 41 , 42  have also exhibited similar results. In fact, methyl-pseudouridine was incorporated into both the Moderna and Pfizer-BioNTech vaccines, but not into CureVac, a third vaccine that entered clinical trials. CureVac had a significantly lower efficacy than the approved vaccines, which could perhaps be attributed to the difference in methyl-pseudouridine content. 41\nThe nitrogenous base cytidine is another target for nucleotide modifications. Specifically, adding a methyl group to carbon 5 of the pyrimidine to form 5-methylcytidine has been effective in increasing the stability and expression of target genes. 34 , 36 , 40  One study also successfully incorporated methylation of adenine to decrease TLR recognition and evade the immune response. 36  While these modifications have seen success in enhancing stability for increased protein production and decreased immune response, it is important to consider the implications of such modifications. Nucleotides are recycled by cells, and considerations must be made about modified nucleotides being incorporated into DNA. Because uridine is only present endogenously in RNA, there is less concern for DNA incorporation when modifying its structure compared with the archetypal nucleotides cytidine and adenine. Notably, 5-methyl cytidine and methyl-6-adenine are enticing mRNA modifications for therapy because they have already been well established as common endogenous nucleotide modifications. 43 – 45\nAccordingly, other methods have been explored to reach these same ends with archetypical nucleotides. 46  One study showed that even one pseudouridine substitution in the codons within the ORF may cause significant hindrance to amino acid addition, thereby impeding translation. 47  Alternatively, expression of the protein can be optimized by engineering the translated region of mRNA to contain the most GC rich codons that represent each amino acid. Each codon consists of a pattern of three nucleotides; with 4 different endogenous nucleotides, 64 different codons exist, each coding for one of only 20 amino acid residues in the genetic code. mRNA transcripts can be engineered by selecting for the codons most rich in guanine and cytidine, which prove more effective at increasing expression while evading the immune system when compared to modified mRNA without sequence optimization. 48  In addition to codon selection, secondary structure is also a significant factor in sequence optimization. Zhang and colleagues have developed an algorithm that can predict stable mRNA transcripts that may assist in the calculated design of mRNA therapeutics. 49 , 50\nAs evidenced in these studies, modulation of nucleotides and codons within the ORF is particularly nuanced because of the implications on protein translation and DNA synthesis. As such, optimization of mRNA efficacy within the ORF of mRNA therapies will continue to evolve as more is discovered about the mechanisms and downstream effects associated with these modifications.\nNatural mRNA transcripts end with repeat additions of adenine (A) nucleotides that contribute to the stability and regulation of expression of the encoded gene. In eukaryotes, the poly(A) tail is typically around 50–100 nucleotides long, though the exact number is dependent on the gene encoded in the transcript and the interactions with different writers and erasers of these residues to regulate expression. 51  The effect of modulating poly(A) tail length is very complex and likely dependent on many factors like cell type and mRNA transcript. Studies have shown that, under various conditions, the optimal poly(A) tail length is 60, 52  100, 53  or 120 25  adenine residues long. Interestingly, one study showed that free poly(A) tails codelivered with mRNA can increase protein expression even when they are not covalently conjugated to the mRNA. 53\nIt has also been shown that modifications to the poly(A) tail itself can be of use. Substitutions of a nonbridging oxygen for a sulfur in the phosphodiester bond connecting adjacent residues of the tail have been less susceptible to degradation and displayed increased expression levels. 54  Azido-modified adenosine incorporation into poly(A) tails has also been shown to increase reporter gene expression in vitro, in addition to its applications for fluorescent labeling via a click chemistry reaction. 55\nAs evidenced by the great variation within poly(A) tail length in endogenous genes, the number of adenine residues terminating an mRNA transcript may be crucial in regulating gene expression and mRNA stability. Consequently, optimization of mRNA therapies must include analysis of the poly(A) tail.\nVarious carriers have been developed for encapsulating RNA to protect it from nucleases, prevent its recognition by the immune system, and increase uptake into cells. Additionally, carriers can aid the RNA in escaping the endosome after being taken up via endocytosis. Many viral and nonviral carrier systems exist to deliver mRNA into cells. For example, viral delivery systems including lentiviruses, adenoviruses, adeno-associated viruses, and herpes viruses are attractive carriers for mRNA as they have highly specific tropisms to various tissues and organs. However, limitations in their loading capacity and immunogenicity are important considerations that may be considered when selecting viral carrier systems. 56  Many nonviral RNA carriers such as lipid nanoparticles, polymeric nanoparticles, polypeptide nanoparticles, and exosomes have also been explored for RNA delivery. While many nonviral platforms may have improved loading and tunability compared with viral vectors, their organ and cell type specificity may be more limited. 57 – 63\nWhile each of these carrier systems displays powerful gene therapy potential, this review will focus on lipid nanoparticles (LNPs) given their role as one of the leading carriers for clinically relevant mRNA delivery. Here, we describe the role of four base components that comprise LNPs – ionizable lipids, structural/phospholipids, cholesterol, and PEGylated lipids ( Figure 2 ).\nIonizable lipids are a class of reversibly amphiphilic small molecules that can become protonated in acidic environments. After uptake into acidic endosomes, this protonation aids in the escape of the mRNA cargo into the cytosol. The ionizable amine, typically tertiary, is present on the head of the molecule and is linked to one or two hydrocarbon-based tails. These tails can vary from around six carbons to 18 carbons with diverse geometries within their saturations, branches, and degradability from heteroatoms. 8 , 64 – 68  Ionizable lipids are the component of LNPs that have the critical function of complexing with the negatively charged mRNA through the interaction with their positively charged headgroup. 69 , 70  This cationic nature is also critical for the LNP’s escape from the endosome after being taken up by cells. 68 , 71 , 72  As such, the ionizable lipids often make up the highest molar ratio of all the components of LNPs. 8\nPhospholipids, like ionizable lipids, consist of a polar headgroup and nonpolar tails. However, they contain a phosphate in place of the amine head. In both approved mRNA therapies, the phospholipid component is the zwitterionic 1,2-disearoyl-sn-glycero-3-phosphatidylcholine (DSPC). 7 , 73 , 74  A function of the phospholipid is essentially to support the structure of the lipid nanoparticle, aid in the endosomal escape by facilitating lamellar to inverted hexagonal phase transition, 75 – 79  and modulate the protein adsorption and subsequent delivery. 80 – 83\nThe poly(ethylene-glycol) (PEG) component of lipid nanoparticles may be conjugated to a lipid anchor that is embedded into the outer layer of the nanoparticle. The highly hydrophilic PEG functional group is exposed on the outside of the LNP. The PEGs in adjacent nanoparticles are repelled from each other and prevent particle aggregation, and the steric hindrance afforded by these long polymer chains minimizes the opsonization of the particles, which increases their circulation time. 84 , 85  However, the presence and implications of anti-PEG antibodies in patients may be complex. 86 – 89\nCholesterol is a bulky, cyclic structure with four chair-conformation rings that is also a key component of LNPs. The highly polar hydroxyl headgroup, the fluidity of the ring formation, and the length of the saturated tail all contribute to the transfection capacity of the LNP. Because of its shape, the presence of cholesterol may prevent the tight packaging of the other LNP components and greatly impacts the fluidity, shape, and efficacy of the LNP. 90 – 94\nEach of these components is tunable, and modulation of each can cause changes in the size, polydispersity index, charge, encapsulation efficiency, biodistribution, and overall efficacy of the LNPs. As such, optimization of the chemistries and molar ratios of each of these components is a large area of research in the field of mRNA delivery. 95 , 96\n\nBecause of the platformable nature of mRNA LNPs, they can be utilized to treat many diseases including many within the scope of female reproductive health. Female reproductive health is an immense field that can encompass a variety of health conditions. Here, we discuss select examples of the usage of mRNA LNPs for application toward female health.\nMany congenital diseases are identifiable before birth but have few treatment options available while the fetus is still in utero. Treating fetal diseases before birth could be particularly advantageous because the immature fetal immune system would be less responsive to mRNA therapy. 97  Additionally, fetuses have increased proliferation of organs and rates of angiogenesis, which may be favorable for increased transfection. 97 , 98  Additionally, lower doses of mRNA therapy may be required because of the smaller weight of the fetus compared with an infant. 97\nAdministration of mRNA therapy to a fetus could be achieved via a minimally invasive intra-amniotic injection similar to the amniocentesis procedure that is commonly administered to pregnant women for genetic testing. 99  LNPs loaded with mRNA have been engineered to remain stable in the amniotic fluid of various species, including humans, and these LNPs effectively deliver mRNA to murine fetal lung fibroblasts in vivo. 99  Alternatively, mRNA has been delivered to fetal tissues via a direct injection into the vitelline vein. mRNA has been successfully delivered to the fetal liver, lungs, and intestines by modulating the LNP formulation administered through this intravenous route. 100  The transfection efficiency of these mRNA LNPs has further been optimized by direct injection into the fetal liver while in utero. 98\nPre-eclampsia occurs when the placenta vasculature is too constricted, which results in maternal hypertension to compensate for blood pressure. This causes fetal growth restriction and can have significant adverse effects on the health of the mother and fetus. 101  Increased expression of placental growth factor (PlGF) or vascular endothelial growth factor (VEGF) could cause vasodilation and rescue this phenotype. LNP carriers would be ideal carriers as they contain PEG, which has been shown to increase uptake into placental cells more readily than other polymers. 102  For a disease relevant application of placental delivery of mRNA LNPs, maternal tail vein injection of mRNA LNPs encoding PlGF 103  and VEGF 104  ( Figure 3A - D ) both caused vasodilation of the placenta in murine models.\nIn the prebirth treatment of congenital diseases, the toxicities associated with both fetal and maternal health must both be of utmost importance. These safety profiles must be extensively studied with particular caution regarding the translation between animal models and human patients.\nWhile delivery of mRNA to developing fetuses is a growing field, the delivery to maternal cells during pregnancy has also been of interest. Delivery of mRNA during pregnancy for maternal health has many important applications. During the COVID-19 pandemic, pregnant women were at an increased risk for hospitalization and ventilation from COVID-19 infection, but were excluded from phase 3 clinical trials. 106 – 108  Vaccine hesitancy in pregnant women was significant, in part because of the initial lack of data. 109  Later, a murine study found no toxicity associated with pregnant mice or fetal mice during pregnancy or lactation after administration of the Pfizer/BioNTech vaccine, with no observed effects on fertility. Neutralizing antibodies were present in both the pregnant mouse and the offspring ( Figure 4A ). 110  Further, human studies of pregnant and nonpregnant individuals have shown that antibody responses were not correlated to gestational age at vaccination. 111  Additionally, though pregnant women showed a slightly lower peak level of IgM and IgA antibodies at 2 weeks postcompletion of the vaccine regimen, there was no difference in the rate of decline for any measured antibody throughout the study ( Figure 4B ). 111  Vaccine-induced antibodies from the mother have also been passively donated to the offspring during pregnancy and lactation. 112  Taken with the safety profiles already established in clinical trials of the vaccine ( Table 1 ), these studies support the use of the vaccine in pregnant women. 109  It is important to note that COVID-19 vaccination, though not yet associated with changes in fertility or pregnancy, may impact menstrual cycles. 113 – 119\nBecause infants are especially susceptible to infections, maternal vaccinations for infections such as influenza, 120 – 122  Zika, 123 – 125  and hepatitis 126  have been utilized to protect newborns. However, this is known to inhibit the baby’s natural antibody production. 127 – 129  An mRNA influenza vaccine in pregnant mice showed a significantly decreased inhibition in the newborn mice’s active immune response to influenza 130 . Though the mechanism may be complex, these results are very encouraging as the mRNA LNP vaccine delivery platform can be modulated with other mRNA transcripts for protection against a variety of viral diseases.\nSexually transmitted infections can have significant adverse effects on the female anatomy. As many of these infections are caused by viruses, there is great potential for utilizing mRNA vaccination strategies to prevent the spread of these STIs. Like the COVID-19 vaccines, mRNA encoding an antigen present on the targeted virus can be encapsulated into LNPs and injected into patients. The mRNA is translated into the corresponding antigen protein, and the adaptive immune system can focus an attack on the specific antigen of interest. 131 – 133  To prevent STIs, mRNA vaccination presents a platform that can be easily adapted for different viruses by substituting the mRNA into the same LNP formulation with the same administration route. Clinical trials utilizing mRNA vaccination for STIs are tabularized in  Table 2  and described herein.\nHerpes simplex virus (HSV) is an STI that has been explored for mRNA vaccination. Around half of Americans aged 14–49 are infected with HSV, with a disproportionately high prevalence in women. Additionally, a higher prevalence is seen in Hispanic and non-Hispanic Black women. 134  HSV can be transmitted through contact with lesions, mucosal surfaces, or secretions. Though often asymptomatic, HSV can cause painful blisters and sores at the site of infection. 134  However, although there are vaccines in clinical trials, there are currently no approved vaccines for the prevention of HSV, 135  an alarming notion given that HSV infections are lifelong. A promising mRNA LNP vaccination has emerged. Trivalent vaccination with three HSV glycoprotein mRNAs prevented infection in the vagina and dorsal root ganglia better than the corresponding protein vaccination and also produced increased T and B cell responses and antibody production with less cell-to-cell spreading in comparison to the corresponding protein vaccination of the same genes ( Figure 5A ). 135 , 136  The trivalent mRNA vaccination was also more effective when infection occurred longer after the immunization, likely because of an increased persistence of antigen-specific memory B cells in the mRNA compared with a protein vaccine. 137  Additionally, though this trivalent mRNA vaccine was designed for type 2 HSV, it was shown to also be effective in protecting against type 1 HSV, 138  and later studies showed that dose-deescalation was possible while still causing total protection from HSV. 139  Additionally, HSV can be passed from mother to newborn  in utero , peripartum, or postpartum, thereby causing significant morbidity and congenital disabilities if left untreated. 140  The same trivalent HSV vaccine was shown to be effective in preventing the passage of this infection in murine models. 141\nThough the monkeypox virus (MPXV) is more prevalent in males (specifically males who have sex with males), 143 , 144  it also significantly affects women as was evidenced in the 2022 global outbreak. 145  This outbreak was significant enough to warrant the WHO’s declaration of it as a Public Health Emergency of International Concern. Monkeypox present with painful lesions at the mouth, anus, or genitals. 145  Two concurrent studies have developed multivalent mRNA vaccines that contain peptides of multiple antigens associated with MPXV and provide robust protection against the virus with no gross toxicity or significantly altered associated pathology ( Figure 5B ). 142 , 146\nThe Zika virus (ZIKAV or ZIKV) is often transmitted via mosquitoes, 149  but the outbreak in the mid-2010s confirmed that transmission can occur via sexual contact. 150 , 151  While the symptoms of this condition are generally mild, including rash, fever, and joint pain, significant congenital disabilities can be caused when the infection occurs during pregnancy. 149  Many LNP mRNA vaccines have been rapidly developed that encode glycoproteins of the ZIKV envelope and induce strong protective immunity against ZIKV infection in mice. 147 , 152 – 157  Some mRNA vaccines have been engineered to prevent congenital transmission and have successfully prevented the transmission of ZIKV from pregnant mice to their offspring, protecting against fetal congenital disabilities ( Figure 6 ). 148 , 158 , 159\nHuman immunodeficiency virus (HIV) is a sexually transmitted disease that begins with flu-like symptoms such as fever, joint pain, fatigue, and rashes, and then progresses into a fatal disease. 162  Globally, HIV is more prevalent in females than in males and can be transmitted sexually or congenitally. 163  HIV and AIDS have been deemed a public health crisis by the United Nations, and there is an urgent need for the development of an HIV vaccine. The use of mRNA LNPs for vaccination may offer a solution. Vaccination with a novel mRNA construct encoding HIV envelope proteins in primates was at least as effective as a protein adjuvant vaccine of the same proteins. Its function was to induce non-neutralizing antibodies (nnAbs) that would mark infected cells for destruction. 164  Multiple mRNA vaccinations for HIV have reached clinical trials already, promoting optimism toward the treatment of this STI with mRNA vaccines ( Table 2 ).\nHPV, or human papillomavirus, is the most common viral STI in the world. 165  It can cause anogenital warts, but its more grave outcome is that it is strongly correlated with the incidence of cervical cancer, anal cancer, and head and neck cancer. 166 – 168  Treatment of these HPV-associated cancers with mRNA vaccination against the HPV infection has shown great promise for both reducing tumor burden and preventing relapse. The immune response is a large contributing factor to the outcomes of HPV+ cancer patients, as high levels of CD8+ tumor-infiltrating cells are correlated to better overall survival. 169  One study showed that such HPV vaccination activated antigen-specific effector cells to attack subcutaneous HPV+ tumors, and circulating memory CD8 +  T cells protected from relapse. 170  Additionally, vaccination with self-amplifying mRNA of three HPV antigens has shown efficacy in eradicating subcutaneous HPV+ tumors at various stages and preventing their relapse. 171  A previous study has shown that HPV vaccination for the treatment of cervical cancer using a traditional vaccine was most effective when combined with the chemotherapeutic agent cisplatin. 172  As such, future mRNA LNP vaccines may incorporate a combinatorial treatment strategy with traditional chemotherapeutics.\n\nIn this review, we discussed the state of the literature on female reproductive health, specifically highlighting mRNA delivery to fetal tissue, treatment of pre-eclampsia, COVID-19 and influenza vaccination of both mother and fetus, and vaccination against STIs including herpes simplex virus, monkeypox virus, Zika virus, human immunodeficiency virus, and human papilloma virus ( Table 3 ,  Figure 7 ). Building on this, it is important to note that additional types of RNA therapy also bear the potential to treat other areas important in female health. For example, microRNA and siRNA have already been explored for the treatment of endometriosis (the presence of endometrial tissue outside of the uterus), 173 , 174  and mRNA therapies could supplement this research. Additionally, uterine fibroids (a type of noncancerous growths within the uterus) have traditionally been treated with surgery or modulators of progesterone or GnRH receptors, 175  and it may be interesting to understand how the use of mRNA therapies could be used to address this condition in the future. Further, polycystic ovarian syndrome (PCOS, another disorder of female reproductive health that is characterized by excess production of androgens by the ovaries, dysfunctional ovulation, and polycystic ovarian morphology) may also represent an interesting disease to target with RNA therapies given that various genes have been implicated in the development of PCOS. 176 , 177  Notably, each of these conditions can contribute to female infertility which may also one day benefit from treatment with RNA therapies.\nLooking forward, it will be interesting to see how mRNA therapy may be leveraged to improve treatments and prognoses of women’s health. The platformable nature of mRNA nanoparticle delivery systems allows for rapid gene therapy development for various diseases, including those associated with female reproductive health. The outlook for mRNA therapy in female reproductive health is encouraging, with new LNP formulations already being developed specifically for safety and efficacy during pregnancy. 178  Building on this, the future of mRNA LNP for application in female health is bright, and it will be exciting to see how these technologies continue to advance from the benchtop to the clinic in the coming years.\n\nFemale reproductive health is an important field of research that, though currently underrepresented, may benefit from the use of mRNA therapy. mRNA LNP therapies offer a modular platform that has the potential to be applied to a wide range of diseases and health concerns. The rapid emergence and success of the COVID-19 vaccine showed the utility of this platform and its capacity to be adapted to evolving issues. With the approval of both the Moderna and Pfizer/BioNTech vaccines, the expanding applications of these platforms with a variety of mRNA transcripts can be used to treat many diseases that are characterized by a loss of function mutation, downregulation of an important gene, or to immunize patients against detrimental viral infections. As reviewed above, this is particularly applicable to issues of women’s health that have been historically underrepresented in research, 1  including sexually transmitted infections and pregnancy-related health issues.\nWhile the use of gene therapy such as mRNA for women’s health can protect and treat women for life-threatening conditions of both mother and fetus, safety concerns must be given particular attention. Though there is yet no evidence of the impacts of the COVID-19 vaccines on fertility, vaccine hesitancy was exacerbated by the prospect of such an impact. 179  The development of future mRNA therapies for reproductive health may therefore benefit from addressing potential impacts on fertility, pregnancy, and menopause in both development and clinical trial stages. Additionally, as evidenced by the COVID-19 vaccine hesitancy present in pregnant and lactating women, 109  attention to the effects that the therapy can have on the fetus will also be of utmost importancesdoi to some patients.","source_license":"CC-BY-4.0","license_restricted":false}