A Review on Treatment of Premature Ovarian Insufficiency: Characteristics, Limitations, and Challenges of Stem Cell versus ExosomeTherapy

Premature ovarian insufficiency (POI) is a complex disorder that can result in varying degrees of infertility. Recently, mesenchymal stem cell (MSC) therapy and its derivatives, such as exosomes, have been introduced as novel strategies for the treatment of POI. This review discusses the features, limitations, and challenges of MSC and exosome therapy in the treatment of POI and provides readers with new insights for comparing and selecting chemical agents, optimizing doses, and other factors involved in study design and treatment strategies. MSC therapy has been shown to improve ovarian function in some animals with POI, but it can also have side effects such as high cost, time-consuming processes, limited lifespan and cell sources, loss of original characteristics during in vitro proliferation, dependence on specific culture environments, potential immune reactions, unknown therapeutic mechanisms, etc. However, exosome therapy is a newer therapy that has not been studied as extensively as MSC therapy, but that it has shown some promise in animal studies. The evidence for the effectiveness of MSC and exosome therapy is still limited, and more research is needed to determine whether these therapies are effective and safe for women with POI. This study presents a new perspective for researchers to advance their research in the fields of cell-based and cell-free therapies.


Introduction
Premature ovarian failure (POF) is a disorder in which women under 40 years of age experience 4-6 months of amenorrhea with high levels of FSH (follicle-stimulating hormone) and low levels of estradiol [1].Te global overall prevalence of POF is 3.5% among women.Furthermore, subgroup analysis shows a prevalence of 11.2% for iatrogenic etiology and 10.5% for autoimmunity [2].Te more precise term for this disorder is premature ovarian insufciency (POI).At any stage of POI, a woman's fertility may be impacted by a drop in the number of early primordial follicles, an increase in follicle destruction or a decrease in the number of apoptotic follicles, and the inability of follicles to respond to gonadotrophin stimulation [1].Various strategies have been employed to remedy POI.
Hormone replacement therapy has been the frst-line strategy, followed by more novel treatments such as stem cell and exosome therapy [3].
Stem cell therapy involves transplanting stem cells from sources like bone marrow, adipose tissue, or umbilical cord blood to promote ovarian tissue regeneration and restore function [4].Reports suggest MSCs inhibit granulosa cell apoptosis and upregulate anti-Müllerian hormone and FSH receptor expression, ofering hope for POF patients and infertile women [5].Moreover, growth diferentiation factor-9 (GDF-9) and stem cell factor (SCF) impact follicle development beyond the primary stage, with GDF-9 promoting primordial follicle formation and growth while FSH infuences granulosa cell development via SCF in an animal model [6].Exosome treatment, on the other hand, is a noncellular therapeutic strategy that takes advantage of the biologically potent characteristics of exosomes, which are nanosized extracellular vesicles released by cells.Proteins, nucleic acids, growth factors, and other bioactive substances that can afect the ovarian microenvironment and promote tissue regeneration are contained within exosomes' cargo [7].Te paracrine efects of exosomes allow for intercellular communication and targeted delivery of bioactive cargo, thus promoting tissue repair [8].

POI
POI is a heterogeneous disorder caused by genetic factors, autoimmune diseases, mitochondrial abnormalities, iatrogenic factors (including chemotherapy, radiotherapy, and surgical procedures), and environmental factors [3].While over 50 genes are known to be related to POI, many cases still lack a clear genetic explanation [9].Premature ovarian insufciency can be treated using a variety of techniques.Although estrogen is thought to be physiologically replaced by hormone replacement treatment (HRT), ovarian function is not recovered.In vitro activation (IVA), mitochondrial activation, stem cell and exosome therapy, biomaterials techniques, and intraovarian platelet-rich plasma (PRP) injection are promising developing treatments for POI treatment.Tese innovative medicines are still in the experimental stage, despite their potential.A thorough assessment of their efcacy and safety is essential before they can be taken into consideration as viable clinical solutions [3].In addition, identifying a marker like anti-Müllerian hormone (AMH) could aid in diagnosing and counseling women at risk for POI and assessing their ovarian reserve.AMH, produced by young ovarian follicles, is strongly correlated with their number, making it a potential diagnostic tool.Furthermore, AMH levels can indicate the degree of gonadal damage in cancer survivors [10].

Stem Cell Therapy
Mesenchymal stem cell therapy, which is used in stem cell therapy, has lately attracted attention for restoring ovarian function in POI.A multipotent and diverse population of cells known as mesenchymal stem cells (MSCs) can develop along the mesodermal lineage (as shown in Figure 1).Hematopoietic markers (CD45, CD34, and CD14) and costimulatory molecules (CD80, CD86, and CD40) are not expressed by these cells.Human MSCs' expression of CD105, CD73, CD71, CD44, CD271, and CD90 is infuenced by the tissue source and culture environment.According to evidence, MSCs release soluble substances such as transforming growth factor-1, interleukin-10 (IL-10), IL-6, and hepatocyte growth factor (HGF) on a regular basis.By inhibiting antigen-specifc T-cell proliferation and encouraging the development of regulatory T cells, MSCs have an immunomodulatory efect.Successful allogeneic transplants have been thoroughly studied due to MSCs' low immunogenicity.When administered in vivo, MSCs have the capacity to stimulate peripheral tolerance.Furthermore, MSCs are intriguing agents for both local and systematic distribution since they may move from blood arteries to the target using their own unique surface molecules.Te clinical therapeutic efectiveness of MSCs, however, mostly rests on their capacity to change the environment of wounded tissue through the physiological activity of stromal cells in the hematopoietic stem cell niche through the secretion of anti-infammatory and antiapoptotic chemicals.Despite the widespread use of MSCs, there is debate concerning the unidentifed long-term negative efects on immune function and tumorigenic potential [11].Te therapeutic benefts of MSC-based therapy are largely attributed to the efects of paracrine factors that promote angiogenesis.However, in aged MSCs, the secretion of these proangiogenic factors, including vascular endothelial growth factor (VEGF), placental growth factor (PGF), and HGF, is reduced.Conversely, the secretion of antiangiogenic factors such as thrombospondin-1 (TBS1) and plasminogen activator inhibitor-1 (PAI-1) is increased.As a result, aging has a detrimental impact on angiogenesis and directly undermines the therapeutic efectiveness of MSCs [12].
Human umbilical cord mesenchymal stem cells (UC-MSCs), which are obtained from the umbilical cord, possess the aforementioned features of MSCs, as well as a younger nature, lower tumorigenicity, and fewer ethical issues [13].Umbilical cords are a great source for easily extracting mesenchymal stem cells.UC-MSCs express human leukocyte antigen major histocompatibility complex I (MHC I) at a low level, as well as CD29, CD73, CD105, and CD90.Tey do not express MHC II molecules, CD14, CD79, CD34, CD45, or HLA-DR, which gives these cells negligible immunogenic features [14,15].UC-MSCs possess immunomodulatory efects by infuencing the diferentiation, proliferation, and activation of T cell subsets while inhibiting B cell proliferation, diferentiation, and other immune cell activities.Tey exhibit robust proliferative abilities and can diferentiate into various cell types under suitable conditions, both in vivo and in vitro.In addition, UC-MSCs contribute to tissue repair and regeneration by secreting growth factors such as HGF, VEGF, stromal cell-derived factor-1 (SDF-1), keratinocyte growth factor (KGF), fbroblast growth factor (FGF), and insulin-like growth factor-1 (IGF-1), which help facilitate cell proliferation and tissue healing.UC-MSCs also play a role in mitigating infammation at the site of injury, and they actively migrate to the injured site for repair.Tis migration is known as the "return" of the MSCs' "nest function" and has been demonstrated prominently in animal experiments under various microenvironmental conditions [16].
It has been demonstrated that UC-MSCs can improve the phosphatidylinositol-3-kinase (PI3K)/Akt signaling in POF-induced rodents via the nerve growth factor (NGF)/ TrKA pathway.Te PI3K/Akt signaling pathway regulates the follicular growth, survival, maturation, and diferentiation of primordial follicles, as well as the prevention of apoptosis.Furthermore, the nerve growth factor receptor (TrkA) mainly activates the PI3K/Akt and mitogenactivated protein kinase (MAPK) signaling pathways, which are essential for the proliferation and survival of cells 2 Veterinary Medicine International [15].In a study, the intravenous injection of two doses of 1 * 10 6 UC-MSCs was able to transfer to the interstitium of the ovaries rather than to the follicles.Tis process prevented the apoptosis and infammation in the granulosa cells in a POF-rodent model [13].As shown in Table 1, diferent doses of UC-MSCs have been given to test their efcacy in restoring ovarian function in the POF model.UC-MSCs appear to have a large therapeutic potential.More consideration must be given to their therapeutic efectiveness, as well as to any potential drawbacks and negative side efects.Female infertility brought on by degenerative factors is one condition for which bone marrow-derived mesenchymal stem cells (BMMSCs) have been touted as potential cures in regenerative medicine [22,37].Studies have shown that folliculogenesis may be afected by bone morphogenic proteins (BMPs), such as BMP-15 and BMP-6.Tese intraovarian subfamilies secreted from the oocyte have a key role in the development of follicles [19].Vascular endothelial growth factor (VEGF), basic fbroblast growth factor (bFGF), insulin-like growth factor 1 (IGF-1), hepatocyte growth factor (HGF), and other cytokines and growth factors are among those secreted by BMMSCs.Angiogenesis, mitogenesis, and antiapoptotic events all depend on these variables.Granulosa cells (GCs) can create a new capillary network thanks to VEGF, an angiogenic cytokine factor.Folliculogenesis results from bFGF's stimulation of the promotion of primordial follicles.IGF-1 has the power to promote GC proliferation, inhibit apoptosis, and enhance antrum follicle development.HGF signifcantly afects follicle maturation and inhibits GC and follicle death in the ovary [22].In this regard, BMMSCs have been applied for stem cell therapy in POF models.
During a woman's menstrual cycle, human endometrial mesenchymal stem cells (EnSCs) are a rich, noninvasive source of multipotent stem cells that can be used for autologous transplantation.In vitro, EnSCs develop quickly and can diferentiate into a variety of cells depending on the particular cell environment.EnSCs express OCT4, CD9, CD29, CD105, SSEA-4, and CD73 but do not express CD34, CD133, HLA class I, or CD45 markers.It was demonstrated that the allogenic transplantation of ESCs is feasible for the dose-dependent regulation of mononuclear cell proliferation.Lai et al. applied EnSCs to investigate their therapeutic efect on ovary preservation in POI models.It was shown that EnSCs could recover the ovarian follicles after chemotherapy in animals [23].
Another potential treatment option for female reproductive issues caused by POI is MSCs generated from human embryonic stem cells (hESC-MSCs).In rats whose ovaries had been damaged by chemotherapy, it was shown that this kind of MSC may stop ovarian apoptosis and encourage ovulation.HESC-MSCs have been made available as an easy-to-expand cell type with a consistent population [19,23,38].Nevertheless, despite all the research and benefts of hESC-MSCs, it is understandable to be concerned about their drawbacks and moral dilemmas.According to studies, hESC-MSCs have the capacity to develop germ-layer malignancies.Te defective transplantation of stem cells derived from embryonic lines may lead to incomplete differentiation.Furthermore, genetic anomalies have been reported in hESC lines in long-term culture [38].
Fetal MSCs can be derived from the liver in early gestation and have long lifespans with appropriate immunomodulatory features.It was reported that FMSCs could restore ovarian function in POI-induced mice, as well as promote human  Veterinary Medicine International Veterinary Medicine International Human [36] Veterinary Medicine International granulosa cell proliferation through the melatonin membrane receptor 1 (MT1).Te evidence suggests that the interaction of melatonin with its receptors (MT1 and MT2) leads to a reduction in the level of reactive oxygen species and the prevention of apoptosis, so that the MT1 and MT2 blockages afect the follicular atresia and porcine GCs and consequently the reproduction mediation.On the other hand, the antioxidant properties of melatonin and the MT1 receptor on cytoprotective activity have been reported in cisplatininduced ovary injury [28].
Te therapeutic efect of adipose-derived stem cells (ADSCs) on ovary failure due to cyclophosphamide (CTX) has been investigated.Te results showed the efectiveness of these types of multipotent stem cells on ovulation and folliculogenesis [29,30].According to Cil et al., ADSCs have a specifc impact on the phosphorylated-mTOR (p-mTOR) and mammalian target of rapamycin (mTOR), which are crucial for oocyte meiosis [30].
Furthermore, the chorionic plate-derived MSCs (CP-MSCs), the multipotent self-renewal adult stem cell, have been applied for the recovery of ovarian function through stimulating ovulation and folliculogenesis in POI models.Tese cells can be easily extracted from the chorionic plate of the human placenta, which is considered medical waste [31].However, the therapeutic efect of autologous MSCs in women with POF disorder suggests a novel strategy that could decline the symptoms of menopause as well as estrogen enhancement.Despite the promising therapy, this study was limited to a few numbers of cases and requires long-term monitoring [39].
In recent years, clinical trials have been conducted on MSCs for various conditions, including autoimmune [40], neurodegenerative, cardiovascular, and bone and cartilage diseases.However, the number of approved MSC treatments worldwide remains limited.Interestingly, Asian countries have approved a higher number of MSC treatments compared to other countries [41].
Overall, when transplanted, MSCs possess the ability to migrate towards injured ovaries, promoting the restoration of secretory function, facilitating follicle formation, and promoting tissue reconstruction in POI models.Similar to white blood cells, MSCs express diferent receptors and cell adhesion molecules that assist in their migration towards the targeted organs, specifcally injured ovaries.Crucially, specifc chemokines bind to MSC receptors, guiding their movement towards the desired tissues.Tis migratory characteristic makes MSCs an excellent choice for regenerative therapies in POI.Once they migrate to the injured ovary, MSCs play a signifcant role in regulating ovarian cell proliferation, apoptosis, immune response, and oxidative stress through their paracrine efects.Tis highlights the critical importance of MSC migration as a key mechanism for enhancing the effectiveness of therapeutic interventions.
Table 1 provides a comprehensive overview of the molecular mechanisms underlying the efectiveness of MSC therapy for POI.Multiple studies emphasize the positive effects of various MSC types on ovarian function.Notably, MSCs have been found to reduce the secretion of infammatory cytokines and FSH, which are often elevated in POI.Conversely, MSCs promote an increase in estrogen levels, anti-Müllerian hormone, and demonstrate improvements in the PI3k/AKT pathway, enhancing angiogenesis within the ovary.Moreover, MSCs extend their impact beyond hormone regulation.Tey play a critical role in inducing and supporting follicular growth, preventing follicular atresia, and inhibiting apoptosis.Together, these orchestrated biological efects hold immense potential for rejuvenating and restoring ovarian function in individuals with POI.

Stem Cell Terapy Limitations and Prospects.
Te therapeutic use of MSCs has faced a number of difculties while receiving a lot of attention for the treatment of numerous illnesses, including those afecting the female reproductive system.Te authors have identifed some of these issues, as shown in Table 1.Controlling the quality of MSCs is difcult.While some groups' extraction procedures are timeconsuming, intrusive, and expensive, others may lose their original characteristics while proliferating in vitro.Other challenges include a short lifespan and cell sources, unidentifed therapeutic methods, the tumorigenicity of stem cell therapy, unclear dosing frequency, and particular growth conditions.Especially in the case of a disease state, it is urgent to have an appropriate and precise estimation for a sufcient number of cells in the transplantation process, which may be afected by apoptosis, infammation, and any special condition of the POI disorder.Over the years, various amounts of stem cells have been administered for POI treatment, and the exact amount has not been determined.However, it seems essential to defne the stage of POI frst based on the chemotherapy agents and their doses, taking into account any probable adverse efects in the long term.Ten, try to use standard concentrations, protocols, and materials for administration.Furthermore, evidence has shown that the physiochemical and mechanical features of the surrounding microenvironment of primordial germ line cells have a signifcant efect on their fate, growth, maturation, and diferentiation.In fact, a three-dimensional structure and biomechanical properties are provided by the natural extracellular matrix (ECM), which has a great role in signaling phenomena, cell-to-cell communication, and consequently tissue development [42,43].In this line, alginate-ECM gels have been used to illustrate the role of ECM and its components in regulating the development of follicles [43].
In addition, scafold-based stem cell transport has been developed to circumvent the main drawbacks of stem cell therapy.Te extremely low cell survival rate in cell treatment is seen as a serious issue.Te survival, adhesion, proliferation, and diferentiation of stem cells must therefore be enhanced by providing a milieu that is similar to the cell niche.Collagen and alginate are examples of natural-based scafolds that have recently been developed and demonstrated to have the ability to awaken POI follicles that are in a dormant state [33,35,36,44].

Exosome Therapy
Exosomes, which are the nanosized extracellular vesicles produced within eukaryotic cell endosomes, have gained signifcant attention in the felds of life sciences research and Veterinary Medicine International biotechnology [45].Tey play a signifcant role in cell-to-cell communication, signaling, and consequently physiological cellular action and development [46].Exosomes are generated through the fusion of exosome-containing endosomes with the plasma membrane, whereas the secretion of microvesicles and apoptotic bodies occurs through direct budding from the plasma membrane.Te biogenesis of exosomes starts with inward budding of the plasma membrane, forming early endosomes, and progresses to the maturation of multivesicular bodies (MVBs), wherein intraluminal vesicles (ILVs) are formed by inward budding of the endosomal membrane.Tese ILVs contain lipids, proteins, and nucleic acids derived from their parent cells [45].Te heterogeneous vesicles are categorized into exosomes, apoptotic bodies, and microvesicles based on their size and biogenesis [46].When processing and separating exosomes, it is crucial to take into account variables including the makeup of the initial sample, the chosen method of separation, and how these variables afect the quality and traits of the fnished products.Ultracentrifugation, ultrafltration, precipitation, immunoafnity capture, and sizeexclusion chromatography are the fve methods that are frequently employed for exosome processing.Tese techniques all generate exosomes, however, to varied degrees of purity and number.Combining isolation methods is a typical strategy to increase exosome yield and purity [45].Exosomes are secreted in physiological and pathological states and are present in follicular fuid (FF).It has been reported that hormonal response, oocyte diferentiation, follicular growth, and the meiosis onset pathways have been regulated by the involvement of FF exosomes [46].Furthermore, the evidence has demonstrated that exosomes carry a variety of microRNAs (miRNAs), some of which, such as miR-100, miR-132, miR-212, and miR-214, directly regulate the meiosis and maturation of follicles [47].
MiRNAs are small noncoding regulatory RNAs that function in posttranscriptional gene regulation with the ability to regulate cellular processes broadly [48].Recent studies have shown that MSC-derived exosomes can promote tissue repair and regeneration, making them an attractive candidate for the treatment of POI (Table 2).Studies have shown that the therapeutic efects of MSCs may be due to their paracrine factors, which include exosomes.Tese bilayered structures appear to have the capacity to overcome some limitations of MSCs, such as vascular blockage due to the large size of cells or fnite lifespan and sources.However, it has been noted that a newly introduced method may overcome the challenge of low extracted numbers of exosomes.Cha et al. reported that their 3D-bioprocessing method has the potential to produce efciently scalable EVs from human MSCs for clinical and/or commercial applications [63].
In addition, research on FF EVs has shown that distinct miRNA types depend on the size and type of follicles.Te types of miRNAs shift from those associated with cell proliferation pathways to those associated with infammatory response pathways when follicles develop and diferentiate into bigger antral ones [64].Small extracellular vesicles derived from embryonic stem cells have the potential to promote the recovery of ovaries in POF mice models by improving folliculogenesis and the proliferation of GCs through the PI3K/AKT signaling pathway [49].MiRNA-21, one of the many miRNAs, has been shown to play a signifcant role in ovarian folliculogenesis by controlling and interacting with a variety of target genes.Consequently, autoimmune POIs have low levels of miRNA-21 expression.MiR-21 has demonstrated a positive link with AMH, E2, uterine size, and ovarian volume in a POI mice model and a negative correlation with FSH and LH [65].Tabet et al. studied amniotic fuid mesenchymal stem cells (AFMSCs) to determine the exosomal miRNA.Tey found that AFMSCs-derived vesicles are a great source of miRNA-21, which prevents apoptosis, induces follicle regeneration, and recovers ovary function in infertile rats through the phosphatase and tensin homolog (PTEN) and PI3K/PTEN pathways [48].Furthermore, AFMSCs-derived exosomes contain miRNA-146a and signifcantly miRNA-10a, which have antiapoptotic efects and inhibit ovarian follicles from atresia in CPA-induced animal models [50].Figure 2(a) shows the schematic diagram of the proposed mechanism of AFMSCs-derived miRNA-146a on damaged GCs.Te exosomal miRNA-369-3p from AFMSCs has similar behavior in POF models through a specifc pathway (Figure 3) [52].Another study showed that human amniotic epithelial cell-derived exosomes include a variety of miRNAs, such as miRNA-1246.HAEC-exosomes have been administered to investigate their efect on ovarian follicles against apoptosis and have shown signifcant efcacy on folliculogenesis [66].It has been reported that there is an interaction between miRNA-17-5P and sirtuin-7 (SIRT7), which can be extracted from HUCMSCs in the ovary.SIRT7 regulates the response of cells to metabolic, oxidative, and genotoxic stresses.In a POI model, the administration of miRNA-17-5P could restore ovarian function, trigger GC proliferation, reduce ROS accumulation, and inhibit SIRT7 expression [53].
HUCMSCs exosomal miRNA-126-3p prevents GC apoptosis through the PIK3R2/PI3K/AKT/mTOR axis in vitro [55].Exosomes derived from HADSCs have the potential to target the SMAD/TGFβ signaling pathway, leading to the proliferation of oocytes and GCs, promoting hormonal secretion and follicle diferentiation [58].Te secretome of human bone marrow MSCs has also been investigated for POF treatment.Te fndings show that this secretome contains exosomal miR-144-5p [59] and miR-644-5p [60], which target PTEN and p53 to prevent GC apoptosis, respectively.Furthermore, the human BMMSC secretome signifcantly afects GCs, thus improving the secretion of GC hormones and stimulating growth and proliferation [69]. 10 Veterinary Medicine International Veterinary Medicine International 12 Veterinary Medicine International Veterinary Medicine International 14 Veterinary Medicine International Menstrual blood-derived stromal cells (MenSCs), according to studies, can help with fertility restoration.In this regard, a rat model was used to study the therapeutic efects of exosomes produced from MenSCs.MenSCsexosomes could enhance ovarian function, restore the ovary cortex, and encourage GC proliferation, according to in vivo research [61].Veterinary Medicine International were acquired subsequent to MSC/exosome therapy to evaluate molecular changes resulting from the treatment.Furthermore, parallel breeding experiments were conducted to compare the restoration of fertility.Both the MSC-treated and exosome-treated groups exhibited reestablished estrous cycles and serum hormone levels compared to untreated mice with POI.Following treatment, the pregnancy rate in the MSC-treated group ranged from 60 to 100%, while the exosome-treated group demonstrated a pregnancy rate of 30 to 50%.Interestingly, regarding long-term efects, the MSCtreated mice consistently maintained a pregnancy rate of 60 to 80% during a second breeding cycle, whereas the exosome-treated group experienced a recurrence of infertility during the second breeding round [70].
In summary, studies have demonstrated the obvious benefts of exosome therapeutics in regenerative medicine and for the treatment of premature ovarian insufciency.However, preclinical trials demonstrating the efcacy and safety of exosome therapy for POI are lacking.

Exosome Terapy Limitations and Prospects.
Although cell-free techniques like exosome therapy are receiving more attention, there are still signifcant obstacles to their usage in POI treatment.Exosomes are excellent suppliers of a variety of miRNAs and other compounds that might modify cellular function, as was previously described.It will need additional research to ascertain the precise mechanism of each miRNA as well as any potential connections between exosomes and other signaling pathways.Determining the precise processes, how they work together, and most crucially, how they relate to the molecules involved in infammation, regulation, and immunomodulation is also crucial.As discussed regarding the challenges of stem cell therapy in POI treatment, there is a signifcant gap in the design of models, applied materials and drugs, and treatment strategies, as well as exosome therapy.Te other main challenges are the lack of standard protocols for the isolation, purifcation, and characterization of MSCderived exosomes, which can lead to variability in the quality and potency of exosomes used for therapy.Exosome-based therapies' safety must also be carefully considered because there is a chance of immune rejection and unintended side efects.In addition, there is no agreement on the administration strategy.Exosomes that are administered conventionally have been demonstrated to quickly leave the bloodstream; 2 hours after injection, they were found in the liver, spleen, lung, and gastrointestinal systems.For the optimum performance of local delivery of exosomes, Riau et al. suggested sustained distribution of exosomes using biodegradable materials like hydrogel [71].Finally, there is no research that determines any probable long-term and systematic administration efects of miRNAs on reproductive diseases.Tus, it is essential to consider the efect of these vesicles on other organs due to their nanosize (Table 3).

Conclusion
In conclusion, mesenchymal stem cells and MSC-derived exosomes hold great promise as potential therapeutic options for the treatment of premature ovarian insufciency.In combination with the wide variety of miRNAs and other chemicals found in exosomes, MSCs have the unusual capacity to specialize into a variety of cell types, which makes them excellent candidates for regaining ovarian function.To efectively utilize their therapeutic potential, a number of issues and restrictions must be resolved.Te absence of established techniques for the isolation, growth, safety, and  [52] Needing to increase the production efciency * [52] Te asterisk ( * ) indicates confrmation for each statement, while the question mark (?) indicates that there is no defnitive answer.16 Veterinary Medicine International characterization of MSCs and exosomes is one of the major difculties.Te viability, efcacy, and reproducibility of the treatments may be impacted by this variation in methodology.Controlling MSC quality is also important because in vitro proliferation and extraction methods can change their original characteristics.In order to guarantee enough cell counts for transplantation, specifed parameters and administration concentrations must be established while taking into account variables like the stage of POI and potential long-term negative consequences.Furthermore, the fate, development, and diferentiation of primordial germ line cells are signifcantly infuenced by the physiochemical and mechanical characteristics of the milieu around them.Collagen and alginate are examples of naturalbased scafolds that have shown potential for improving the viability and stimulation of dormant follicles in POI.Scafold-based delivery systems ofer a milieu that resembles the cell niche, enhancing stem cells' adhesion, proliferation, and diferentiation.Exosome therapy has drawn interest as a cell-free approach; however, there are still issues to be solved.Exosomal miRNAs' precise mechanisms of action and interactions with other signaling pathways must be clarifed through further study, which is now underway.Tis information will be useful in developing more potent therapy strategies for POI.Taking everything into account, it is clear that while MSCs and exosomes produced from MSCs have a great deal of potential to treat POI, further study is required to overcome current obstacles and improve the delivery, characterization, and administration protocols.
Taking on these issues will open the door for the creation of efcient, standardized, and secure therapy approaches for women with POI.

Figure 1 :
Figure 1: Te multipotency properties of MSCs.Tis image illustrates diferentiation and self-renewal (curved arrow).Ability of MSCs in the bone-marrow cavity in vivo.

Table 1 :
Various types of MSCs application in POI treatment.

Table 2 :
Various types of MSCs-derived exosomes application in POI treatment.

Table 3 :
Overall comparison description of the stem cell-versus exosome therapy in POI.