A new material for tissue engineered vagina reconstruction: Acellular porcine vagina matrix

Desktop-Stereolithography 3D Printing of a Decellularized Extracellular Matrix/Mesenchymal Stem Cell Exosome Bioink for Vaginal Reconstruction

BACKGROUND

3D-printing is widely used in regenerative medicine and is expected to achieve vaginal morphological restoration and true functional reconstruction. Mesenchymal stem cells-derived exosomes (MSCs-Exos) were applyed in the regeneration of various tissues. The current study aimed to explore the effctive of MSCs-Exos in vaginal reconstruction.

METHODS

In this work, hydrogel was designed using decellularized extracellular matrix (dECM) and gelatin methacrylate (GelMA) and silk fibroin (SF). The biological scaffolds were constructed using desktop-stereolithography. The physicochemical properties of the hydrogels were evaluated; Some experiments have been conducted to evaluate exosomes' effect of promotion vaginal reconstruction and to explore the mechanism in this process.

RESULTS

It was observed that the sustained release property of exosomes in the hydrogel both in vitro and in vitro.The results revealed that 3D scaffold encapsulating exosomes expressed significant effects on the vascularization and musule regeneration of the regenerative vagina tissue. Also, MSCs-Exos strongly promoted vascularization in the vaginal reconstruction of rats, which may through the PI3K/AKT signaling pathway.

CONCLUSION

The use of exosome-hydrogel composites improved the epithelial regeneration of vaginal tissue, increased angiogenesis, and promoted smooth muscle tissue regeneration. 3D-printed, lumenal scaffold encapsulating exosomes might be used as a cell-free alternative treatment strategy for vaginal reconstruction.

Biochemical and immunomodulatory insights of extracellular matrix from decellularized human whole cervix: recellularization andin vivoECM remodeling interplay

Extracellular matrix (ECM) rich whole organ bio-scaffolds, preserving structural integrity and essential growth factors, has potential towards regeneration and reconstruction. Women with cervical anomalies or trauma can benefit from clinical cervicovaginal repair using constructs rich in site specific ECM. In this study, complete human cervix decellularization was achieved using a modified perfusion-based stir bench top decellularization method. This was followed by physico-chemical processes including perfusion of ionic agents, enzymatic treatment and washing using detergent solutions for a duration of 10-12 d. Histopathological analysis, as well as DNA quantification confirmed the efficacy of the decellularization process. Tissue ultrastructure integrity was preserved and the same was validated via scanning electron microscopy and transmission electron microscopy studies. Biochemical analysis and structural characterizations like Fourier transform infrared, Raman spectroscopy of decellularized tissues demonstrated preservation of important proteins, crucial growth factors, collagen, and glycosaminoglycans.In vitrostudies, using THP-1 and human umbilical vein endothelial cell (HUVEC) cells, demonstrated macrophage polarization from M1 to M2 and vascular functional genes enhancement, respectively, when treated with decellularized human cervical matrix (DHCp). Crosslinked DHC scaffolds were recellularized with site specific human cervical epithelial cells and HUVEC, showing non-cytotoxic cell viability and enhanced proliferation. Furthermore, DHC scaffolds showed immunomodulatory effectsin vivoon small rodent model via upregulation of M2 macrophage genes as compared to decellularized rat cervix matrix scaffolds (DRC). DHC scaffolds underwent neo-vascularization followed by ECM remodeling with enhanced tissue integration.

Alternative Biological Material for Tissue Engineering of the Vagina: Porcine-Derived Acellular Vaginal Matrix

BACKGROUND

Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome is a severe congenital disorder characterized by vaginal hypoplasia caused by dysplasia of the Müllerian duct. Patients with MRKH syndrome often require nonsurgical or surgical treatment to achieve satisfactory vaginal length and sexual outcomes. The extracellular matrix has been successfully used for vaginal reconstruction.

METHODS

In this study, we developed a new biological material derived from porcine vagina (acellular vaginal matrix, AVM) to reconstruct the vagina in Bama miniature pigs. The histological characteristics and efficacy of acellularization of AVM were evaluated, and AVM was subsequently transplanted into Bama miniature pigs to reconstruct the vaginas.

RESULTS

Macroscopic analysis showed that the neovaginas functioned well in all Bama miniature pigs with AVM implants. Histological analysis and electrophysiological evidence indicated that morphological and functional recovery was restored in normal vaginal tissues. Scanning electron microscopy showed that the neovaginas had mucosal folds characteristics of normal vagina. No significant differences were observed in the expression of CK14, HSP47, and α-actin between the neovaginas and normal vaginal tissues. However, the expression of estrogen receptor (ER) was significantly lower in the neovaginas than in normal vaginal tissues. In addition, AVM promoted the expression of β-catenin, c-Myc, and cyclin D1. These results suggest that AVM might promotes vaginal regeneration by activating the β-catenin/c-Myc/cyclin D1 pathway.

CONCLUSION

This study reveals that porcine-derived AVM has potential application for vaginal regeneration.

Biomedical Application of Decellularized Scaffolds

Tissue loss and end-stage organ failure are serious health problems across the world. Natural and synthetic polymer scaffold material based artificial organs play an important role in the field of tissue engineering and organ regeneration, but they are not from the body and may cause side effects such as rejection. In recent years, the biomimetic decellularized scaffold based materials have drawn great attention in the tissue engineering field for their good biocompatibility, easy modification, and excellent organism adaptability. Therefore, in this review, we comprehensively summarize the application of decellularized scaffolds in tissue engineering and biomedicine in recent years. The preparation methods, modification strategies, construction of artificial tissues, and application in biomedical applications are discussed. We hope that this review will provide a useful reference for research on decellularized scaffolds and promote their application tissue engineering.

Creation of a decellularized vaginal matrix from healthy human vaginal tissue for potential vagina reconstruction: experimental studies

BACKGROUND

When a disorder causes the absence of a healthy, full-size vagina, various neovaginal creation methods are available. Sometimes dilation or stretching of the vaginal cavity is sufficient, but intestinal or dermal flap tissue is generally required. However, different inherent tissue properties cause complications. Therefore, a lost body part should be replaced with a similar material. The use of organ-specific acellular vaginal tissue carries great potential, as its similar architecture and matrix composition make it suitable for vaginal regeneration.

METHODS

The authors developed an optimized protocol for decellularization of healthy human vaginal tissue. Resected colpectomy tissue from 12 healthy transgender patients was used. Successful decellularization was confirmed by applying acellular criteria from in-vivo remodeling reports. Suitability as a tissue-mimicking scaffold for vaginal reconstruction was determined by visible structural features, biocompatibility during stretching, and the presence of visible collagen, elastin, laminin, and fibronectin.

RESULTS

Histological examination confirmed the preservation of structural features, and minimal cellular residue was seen during fluorescence microscopy, DNA and RNA quantification, and fragment length examination. Biomechanical testing showed decreased peak load (55%, P <0.05), strain at rupture (23%, P <0.01), and ultimate tensile stress (55%, P <0.05) after decellularization, while the elastic modulus (68%) did not decrease significantly. Fluorescence microscopy revealed preserved Fibronectin-I/II/III and Laminin-I/II, while Collagen-I and Ficolin-2B were decreased but mostly retained.

CONCLUSIONS

The absence of cellular residue, moderately altered biomechanical extracellular matrix properties, and mostly preserved structural proteins appear to make our decellularized human vaginal matrix a suitable tissue-mimicking scaffold for vagina transplantation when tissue survival through vascularization and innervation are accomplished in the future.

Vaginal reconstruction with a double-sided biomembrane-a preclinical experimental study on large animals

Tissue engineering techniques bring the promise of vaginal reconstruction with low invasiveness and fewer complications. However, existing biomaterial scaffolds remain limited in efficient vaginal recovery, focusing only on regenerating an epithelial layer, but muscle layers are missing or abnormal. The lack of a multi-tissue hierarchical structure in the reconstructed vagina leads to shrinking, stenosis, and fibrosis. Here, an acellular matrix named a double-sided biomembrane (DBM) is demonstrated for vaginal recovery. The regeneration of epithelial and muscle layers is achieved simultaneously since the smooth side of the DBM is helpful for guiding epithelial cell growth, while its loose and porous side guides muscle cell growth. In addition, the DBM demonstrates excellent mechanical properties similar to vaginal tissue, and hydrophilicity. Therefore, neovaginas were observed in the fourth and twelfth weeks after DBMs were transplanted to repair full-thickness vaginal defects (4 cm) that we established in large animals. The DBMs can effectively promote rapid epithelialization, the formation of large muscle bundles, higher rates of angiogenesis, and the restoration of physiological function in a neovagina. That is, the injured vagina achieves nearly complete recovery in anatomy and function, similar to a normal vagina. These preclinical results indicate that the DBM has prospects for vaginal injury repair.

New Solutions for Old Problems: How Reproductive Tissue Engineering Has Been Revolutionizing Reproductive Medicine

Acquired disorders and congenital defects of the male and female reproductive systems can have profound impacts on patients, causing sexual and endocrine dysfunction and infertility, as well as psychosocial consequences that affect their self-esteem, identity, sexuality, and relationships. Reproductive tissue engineering (REPROTEN) is a promising approach to restore fertility and improve the quality of life of patients with reproductive disorders by developing, replacing, or regenerating cells, tissues, and organs from the reproductive and urinary systems. In this review, we explore the latest advancements in REPROTEN techniques and their applications for addressing degenerative conditions in male and female reproductive organs. We discuss current research and clinical outcomes and highlight the potential of 3D constructs utilizing biomaterials such as scaffolds, cells, and biologically active molecules. Our review offers a comprehensive guide for researchers and clinicians, providing insights into how to reestablish reproductive tissue structure and function using innovative surgical approaches and biomaterials. We highlight the benefits of REPROTEN for patients, including preservation of fertility and hormonal production, reconstruction of uterine and cervical structures, and restoration of sexual and urinary functions. Despite significant progress, REPROTEN still faces ethical and technical challenges that need to be addressed. Our review underscores the importance of continued research in this field to advance the development of effective and safe REPROTEN approaches for patients with reproductive disorders.

Extracellular Matrix-Based and Electrospun Scaffolding Systems for Vaginal Reconstruction

Congenital vaginal anomalies and pelvic organ prolapse affect different age groups of women and both have significant negative impacts on patients' psychological well-being and quality of life. While surgical and non-surgical treatments are available for vaginal defects, their efficacy is limited, and they often result in long-term complications. Therefore, alternative treatment options are urgently needed. Fortunately, tissue-engineered scaffolds are promising new treatment modalities that provide an extracellular matrix (ECM)-like environment for vaginal cells to adhere, secrete ECM, and be remodeled by host cells. To this end, ECM-based scaffolds or the constructs that resemble ECM, generated by self-assembly, decellularization, or electrospinning techniques, have gained attention from both clinicians and researchers. These biomimetic scaffolds are highly similar to the native vaginal ECM and have great potential for clinical translation. This review article aims to discuss recent applications, challenges, and future perspectives of these scaffolds in vaginal reconstruction or repair strategies.

Advances of xenogeneic ovarian extracellular matrix hydrogels for in vitro follicle development and oocyte maturation

Research aimed at preserving female fertility is increasingly using bioengineering techniques to develop new platforms capable of supporting ovarian cell function in vitro and in vivo. Natural hydrogels (alginate, collagen, and fibrin) have been the most exploited approaches; however they are biologically inert and/or biochemically simple. Thus, establishing a suitable biomimetic hydrogel from decellularized ovarian cortex (OC) extracellular matrix (OvaECM) could provide a complex native biomaterial for follicle development and oocyte maturation. The objectives of this work were (i) to establish an optimal protocol to decellularize and solubilize bovine OC, (ii) to characterize the histological, molecular, ultrastructural, and proteomic properties of the resulting tissue and hydrogel, and (iii) to assess its biocompatibility and adequacy for murine in vitro follicle growth (IVFG). Sodium dodecyl sulfate was identified as the best detergent to develop bovine OvaECM hydrogels. Hydrogels added into standard media or used as plate coatings were employed for IVFG and oocyte maturation. Follicle growth, survival, hormone production, and oocyte maturation and developmental competence were evaluated. OvaECM hydrogel-supplemented media best supported follicle survival, expansion, and hormone production, while the coatings provided more mature and competent oocytes. Overall, the findings support the xenogeneic use of OvaECM hydrogels for future human female reproductive bioengineering.

Tissue Engineering Neovagina for Vaginoplasty in Mayer-Rokitansky-Küster-Hauser Syndrome and Gender Dysphoria Patients: A Systematic Review

Background: Vaginoplasty is a surgical solution to multiple disorders, including Mayer-Rokitansky-Küster-Hauser syndrome and male-to-female gender dysphoria. Using nonvaginal tissues for these reconstructions is associated with many complications, and autologous vaginal tissue may not be sufficient. The potential of tissue engineering for vaginoplasty was studied through a systematic bibliography search. Cell types, biomaterials, and signaling factors were analyzed by investigating advantages, disadvantages, complications, and research quantity. Search Methods: A systematic search was performed in Medline, EMBASE, Web of Science, and Scopus until March 8, 2022. Term combinations for tissue engineering, guided tissue regeneration, regenerative medicine, and tissue scaffold were applied, together with vaginoplasty and neovagina. The snowball method was performed on references and a Google Scholar search on the first 200 hits. Original research articles on human and/or animal subjects that met the inclusion (reconstruction of vaginal tissue and tissue engineering method) and no exclusion criteria (not available as full text; written in foreign language; nonoriginal study article; genital surgery other than neovaginal reconstruction; and vaginal reconstruction with autologous or allogenic tissue without tissue engineering or scaffold) were assessed. The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) checklist, the Newcastle-Ottawa Scale, and the Gold Standard Publication Checklist were used to evaluate article quality and bias. Outcomes: A total of 31 out of 1569 articles were included. Data extraction was based on cell origin and type, biomaterial nature and composition, host species, number of hosts and controls, neovaginal size, replacement fraction, and signaling factors. An overview of used tissue engineering methods for neovaginal formation was created, showing high variance of cell types, biomaterials, and signaling factors and the same topics were rarely covered multiple times. Autologous vaginal cells and extracellular matrix-based biomaterials showed preferential properties, and stem cells carry potential. However, quality confirmation of orthotopic cell-seeded acellular vaginal matrix by clinical trials is needed as well as exploration of signaling factors for vaginoplasty. Impact statement General article quality was weak to sufficient due to unreported cofounders and incomplete animal study descriptions. Article quality and heterogenicity made identification of optimal cell types, biomaterials, or signaling factors unreliable. However, trends showed that autologous cells prevent complications and compatibility issues such as healthy cell destruction, whereas stem cells prevent cross talk (interference of signaling pathways by signals from other cell types) and rejection (but need confirmation testing beyond animal trials). Natural (orthotopic) extracellular matrix biomaterials have great preferential properties that encourage future research, and signaling factors for vascularization are important for tissue engineering of full-sized neovagina.

Preparation and Use of Decellularized Extracellular Matrix for Tissue Engineering

The multidisciplinary fields of tissue engineering and regenerative medicine have the potential to revolutionize the practise of medicine through the abilities to repair, regenerate, or replace tissues and organs with functional engineered constructs. To this end, tissue engineering combines scaffolding materials with cells and biologically active molecules into constructs with the appropriate structures and properties for tissue/organ regeneration, where scaffolding materials and biomolecules are the keys to mimic the native extracellular matrix (ECM). For this, one emerging way is to decellularize the native ECM into the materials suitable for, directly or in combination with other materials, creating functional constructs. Over the past decade, decellularized ECM (or dECM) has greatly facilitated the advance of tissue engineering and regenerative medicine, while being challenged in many ways. This article reviews the recent development of dECM for tissue engineering and regenerative medicine, with a focus on the preparation of dECM along with its influence on cell culture, the modification of dECM for use as a scaffolding material, and the novel techniques and emerging trends in processing dECM into functional constructs. We highlight the success of dECM and constructs in the in vitro, in vivo, and clinical applications and further identify the key issues and challenges involved, along with a discussion of future research directions.

Partial Reconstruction of Uterus Cervix in Rat by Decellularized Human Uterine Cervical Scaffold Combined with Adipose-Derived Stem Cells (ADSCs)

Surgical management for cervical malformation remains as the main therapeutic challenge for gynecologists. A theoretical alternative is to generate a bioengineered uterus cervix, which requires scaffold structure and appropriate cellular constituents. Here, human uterine cervical tissue was decellularized with detergents to produce an acellular scaffold that retained extracellular matrix (ECM), characterized through histochemical studies and DNA assessments. Recellularized scaffold was then established by decellularized scaffold reseeding with adipose-derived stem cells (ADSCs) isolated from rats. We tested these bioengineering samples in a rat model of partial cervical defect and found that recellularized scaffold improved regeneration abilities of the uterine cervix, promoted better vascularization, and achieved positive pregnancy outcomes. These results suggest that decellularized human uterine cervical scaffold combined with ADSCs could be used for uterine cervical regeneration and provide insights into treatments for cervical malformation.

Drug-free in vitro activation combined with 3D-bioprinted adipose-derived stem cells restores ovarian function of rats with premature ovarian insufficiency

BACKGROUND

Emerging drug-free in vitro activation (IVA) technique enables patients with premature ovarian insufficiency (POI) to restore ovarian function and conceive their own genetic offspring. However, various issues have greatly restricted its clinical application. Transplantation of adipose-derived stem cells (ADSCs) has promising roles in restoring ovarian function of rats with POI, but insufficient retention has greatly hampered their efficiency. Here, we designed a 3D-bioprinted engineering ovary composed of drug-free IVA and ADSCs, which may prolong the retention of ADSCs and construct an early vascular microenvironment, thus compensating for the disadvantages of drug-free IVA to some extent and ameliorating impaired ovarian function in the POI rats.

METHODS

After intraperitoneal injection of cyclophosphamide, the POI model rats were randomized into 5 groups: (1) POI group; (2) ovarian fragments group; (3) 3D scaffold combined with ovarian fragments group; (4) ovarian fragments combined with ADSCs group; (5) 3D scaffold with ADSCs combined with ovarian fragments as 3D-bioprinted engineering ovary group. Normal rats were identified as the control group. The localization of CM-Dil-labeled ADSCs and co-localization with CD31 were observed to examine the distribution and underlying mechanism of differentiation. Histomorphological and immunohistochemical analyses were performed to calculate follicle number and assess proliferation and apoptosis of granulosa cells (GCs). Immunofluorescence staining was used to evaluate angiogenesis. Hormone levels were measured to evaluate the restoration of endocrine axis. Western blot analysis and RT-PCR were conducted to explore the potential mechanism.

RESULTS

CM-Dil-labeled ADSCs were distributed in the interstitium of ovaries and had significantly higher retention in the 3D-bioprinted engineering ovary group. Several regions of the co-staining for CM-Dil and CD31 were in the area of vascular endothelial cells. Meanwhile, the follicle counts, GCs proliferation, neoangiogenesis, and hormone levels were significantly improved in the 3D-bioprinted engineering ovary group, as compared with other groups. Furthermore, the ovarian function was ameliorated and angiogenesis was promoted through regulating the PI3K/AKT pathway.

CONCLUSION

Our results suggested that 3D-bioprinted engineering ovary had great potential for restoring impaired ovarian function of rats with POI, which could compensate for the disadvantages of drug-free IVA to some extent.

Future Challenges and Opportunities of Extracellular Matrix Hydrogels in Female Reproductive Medicine

Bioengineering and reproductive medicine have progressed shoulder to shoulder for several decades. A key point of overlap is the development and clinical translation of technologies to support reproductive health, e.g., scaffold-free constructs, polymeric scaffolds, bioprinting or microfluidics, and hydrogels. Hydrogels are the focus of intense study, and those that are derived from the extracellular matrix (ECM) of reproductive tissues and organs are emerging as promising new players given their results in pre-clinical models. This literature review addresses the recent advances in the use of organ-specific ECM hydrogels in reproductive medicine, considering the entire female reproductive tract. We discuss in-depth papers describing the development of ECM hydrogels, their use in in vitro models, and their in vivo application in preclinical studies. We also summarize the functions of hydrogels, including as grafts, carriers for cell transplantation, or drug depots, and present the potential and possible scope for use of ECM hydrogels in the near future based on recent scientific advances.

A physiologically relevant, estradiol‐17β [E2]‐responsive in vitro tissue‐engineered model of the vaginal epithelium for vaginal tissue research

Aims

There are many situations where preclinical models of the human vagina would be valuable for in vitro studies into the pathophysiology of vaginally transmitted diseases, microbicide efficacy, irritability testing, and particularly, for assessing materials to be inserted in the vagina for support of the pelvic floor. The aim of this study is to develop a physiologically relevant, low cost, and ethically suitable model of the vagina using sheep vaginal tissue (SVT) to reduce the need for animal testing in gynecological research.

Methods

Tissue‐engineered (TE) vaginal models were developed by culturing primary vaginal epithelial cells and vaginal fibroblasts, isolated from the native SVTs on decellularized sheep vaginal matrices at an air–liquid interface. Morphological analyses of the models were conducted by performing hematoxylin and eosin staining and further characterization was done by immunohistofluorescence (IHF) of structural proteins and cytokeratins.

Results

Histological analysis of the models revealed a gradual formation of a stratified epithelium on our decellularized matrices and cell metabolic activity remained high for 21 days as measured by the resazurin assay. Our models showed a dose‐dependent response to estradiol‐17β [E₂] with an increase in the vaginal epithelium thickness and cellular proliferation under higher E₂ concentrations (100–400 pg/ml). The physiological relevance of these results was confirmed by the IHF analysis of Ki67, and cytokeratins 10 and 19 expression.

Conclusion

In this study, we have developed an estradiol‐responsive TE vaginal model that closely mimics the structural and physiological properties of the native SVT.

Cell-Free Fat Extract Prevents Vaginal Atrophy in an Ovariectomized Model by Promoting Proliferation of Vaginal Keratinocytes and Neovascularization

BACKGROUND

Most perimenopausal and postmenopausal women experience estrogen deficiency-induced vaginal atrophy. However, estrogen replacement therapy has contraindications and side effects, which makes it unsuitable for most women. Cell-free fat extract (CEFFE) has pro-proliferative and proangiogenic tissue regeneration activities.

OBJECTIVES

The purpose of this study was to evaluate the effect of topical application of CEFFE in the vagina and the effect of CEFFE on vaginal keratinocytes.

METHODS

Ovariectomized mice were treated with CEFFE via vaginal topical application for 2 weeks. The vaginal mucosal cell layer number, mucosal thickness, and vaginal collagen volume were determined by histologic analyses. Vaginal mucosa proliferation and lamina propria angiogenesis were evaluated with anti-proliferating cell nuclear antigen and anti-CD31 staining, respectively. For in vitro analysis, VK2/E6E7 cells were administered, increasing the CEFFE concentration. Cell proliferation and cell-cycle distribution were analyzed by Cell Counting Kit 8 assay and flow cytometry, respectively. Mucosal migration was evaluated with a wound-healing assay. The expression of Ki-67 and estrogen-related proteins was detected by western blotting.

RESULTS

CEFFE-treated mice showed increased mucosal thickness and number of vaginal mucosal cell layers and reduced vaginal atrophy compared to ovariectomized mice. The number of proliferating cell nuclear antigen-positive cells and CD31-positive capillaries also increased. In addition, CEFFE promoted the proliferation and migration of VK2/E6E7 cells, upregulated the expression of Ki-67, and inhibited the expression of estrogen-related proteins and the PI3K/AKT pathway.

CONCLUSIONS

CEFFE prevents estrogen deficiency-induced vaginal atrophy by promoting vaginal mucosal proliferation and increasing neovascularization, but not through the estrogen/estrogen receptor pathway, in an ovariectomized mouse model.

OUP accepted manuscript

BACKGROUND

To provide the optimal milieu for implantation and fetal development, the female reproductive system must orchestrate uterine dynamics with the appropriate hormones produced by the ovaries. Mature oocytes may be fertilized in the fallopian tubes, and the resulting zygote is transported toward the uterus, where it can implant and continue developing. The cervix acts as a physical barrier to protect the fetus throughout pregnancy, and the vagina acts as a birth canal (involving uterine and cervix mechanisms) and facilitates copulation. Fertility can be compromised by pathologies that affect any of these organs or processes, and therefore, being able to accurately model them or restore their function is of paramount importance in applied and translational research. However, innate differences in human and animal model reproductive tracts, and the static nature of 2D cell/tissue culture techniques, necessitate continued research and development of dynamic and more complex in vitro platforms, ex vivo approaches and in vivo therapies to study and support reproductive biology. To meet this need, bioengineering is propelling the research on female reproduction into a new dimension through a wide range of potential applications and preclinical models, and the burgeoning number and variety of studies makes for a rapidly changing state of the field.

OBJECTIVE AND RATIONALE

This review aims to summarize the mounting evidence on bioengineering strategies, platforms and therapies currently available and under development in the context of female reproductive medicine, in order to further understand female reproductive biology and provide new options for fertility restoration. Specifically, techniques used in, or for, the uterus (endometrium and myometrium), ovary, fallopian tubes, cervix and vagina will be discussed.

SEARCH METHODS

A systematic search of full-text articles available in PubMed and Embase databases was conducted to identify relevant studies published between January 2000 and September 2021. The search terms included: bioengineering, reproduction, artificial, biomaterial, microfluidic, bioprinting, organoid, hydrogel, scaffold, uterus, endometrium, ovary, fallopian tubes, oviduct, cervix, vagina, endometriosis, adenomyosis, uterine fibroids, chlamydia, Asherman’s syndrome, intrauterine adhesions, uterine polyps, polycystic ovary syndrome and primary ovarian insufficiency. Additional studies were identified by manually searching the references of the selected articles and of complementary reviews. Eligibility criteria included original, rigorous and accessible peer-reviewed work, published in English, on female reproductive bioengineering techniques in preclinical (in vitro/in vivo/ex vivo) and/or clinical testing phases.

OUTCOMES

Out of the 10 390 records identified, 312 studies were included for systematic review. Owing to inconsistencies in the study measurements and designs, the findings were assessed qualitatively rather than by meta-analysis. Hydrogels and scaffolds were commonly applied in various bioengineering-related studies of the female reproductive tract. Emerging technologies, such as organoids and bioprinting, offered personalized diagnoses and alternative treatment options, respectively. Promising microfluidic systems combining various bioengineering approaches have also shown translational value.

WIDER IMPLICATIONS

The complexity of the molecular, endocrine and tissue-level interactions regulating female reproduction present challenges for bioengineering approaches to replace female reproductive organs. However, interdisciplinary work is providing valuable insight into the physicochemical properties necessary for reproductive biological processes to occur. Defining the landscape of reproductive bioengineering technologies currently available and under development for women can provide alternative models for toxicology/drug testing, ex vivo fertility options, clinical therapies and a basis for future organ regeneration studies.

Decellularization Methods of Vagina and Cervix in Tissue Engineering

The vagina is a fibromuscular elastic tubular tract that connects the cervix with the outer genitals and has an important function discharging uterine secretions, sexual intercourse and acts as the passage for the full-term fetus. Currently, a new field of investigation which aims to design tissues and organs similar to their native origin has been developed recently and was named regenerative medicine (tissue engineering and bioengineering). Malformations in cervix tissue represent a hard challenge for medicine. Experts in bioengineering have tried to reconstruct vaginas or cervix with the aim to achieve cervicovaginal disorders, most of them with congenital cause. However, only few research groups have launched themselves upon the decellularization. The aim of this chapter is investigating the decellularization methods for cervix and vaginal tissues.

Ovarian Decellularized Bioscaffolds Provide an Optimal Microenvironment for Cell Growth and Differentiation In Vitro

Ovarian failure is the most common cause of infertility. Although numerous strategies have been proposed, a definitive solution for recovering ovarian functions and restoring fertility is currently unavailable. One innovative alternative may be represented by the development of an “artificial ovary” that could be transplanted in patients for re-establishing reproductive activities. Here, we describe a novel approach for successful repopulation of decellularized ovarian bioscaffolds in vitro. Porcine whole ovaries were subjected to a decellularization protocol that removed the cell compartment, while maintaining the macrostructure and microstructure of the original tissue. The obtained bioscaffolds were then repopulated with porcine ovarian cells or with epigenetically erased porcine and human dermal fibroblasts. The results obtained demonstrated that the decellularized extracellular matrix (ECM)-based scaffold may constitute a suitable niche for ex vivo culture of ovarian cells. Furthermore, it was able to properly drive epigenetically erased cell differentiation, fate, and viability. Overall, the method described represents a powerful tool for the in vitro creation of a bioengineered ovary that may constitute a promising solution for hormone and fertility restoration. In addition, it allows for the creation of a suitable 3D platform with useful applications both in toxicological and transplantation studies.

Genitourinary Tissue Engineering: Reconstruction and Research Models

Tissue engineering is an emerging field of research that initially aimed to produce 3D tissues to bypass the lack of adequate tissues for the repair or replacement of deficient organs. The basis of tissue engineering protocols is to create scaffolds, which can have a synthetic or natural origin, seeded or not with cells. At the same time, more and more studies have indicated the low clinic translation rate of research realised using standard cell culture conditions, i.e., cells on plastic surfaces or using animal models that are too different from humans. New models are needed to mimic the 3D organisation of tissue and the cells themselves and the interaction between cells and the extracellular matrix. In this regard, urology and gynaecology fields are of particular interest. The urethra and vagina can be sites suffering from many pathologies without currently adequate treatment options. Due to the specific organisation of the human urethral/bladder and vaginal epithelium, current research models remain poorly representative. In this review, the anatomy, the current pathologies, and the treatments will be described before focusing on producing tissues and research models using tissue engineering. An emphasis is made on the self-assembly approach, which allows tissue production without the need for biomaterials.

Co-culture with peritoneum mesothelial stem cells supports the in vitro growth of mouse ovarian follicles

The important roles played by the ovarian microenvironment and cell interactions in folliculogenesis suggest promising approaches for in vivo growth of ovarian follicles using appropriate scaffolds containing suitable cell sources. In this study, we have investigated the growth of early preantral follicles in the presence of decellularized mesenteric peritoneal membrane (MPM), peritoneum mesothelial stem cells (PMSCs), and conditioned medium (CM) of PMSCs. MPM of mouse was first decellularized; PMSCs were isolated from MPM and cultured and their conditioned medium (CM) was collected. Mouse follicles were separated into four groups: (1) culture in base medium (control), (2) culture in decellularized MPM (DMPM), (3) co-culture with PMSCs (Co-PMSCs), and (4) culture in CM of PMSCs (CM-PMSCs). Qualitative and quantitative assessments were performed to evaluate intact mesenteric peritoneal membrane (IMPM) as well as decellularized ones. After culturing the ovarian follicles, follicular and oocyte diameter, viability, eccentric oocyte percentage, and estradiol hormone amounts were evaluated. Quantitative and qualitative evaluations confirmed removal of cells and retention of the essential fibers in MPM after the decellularization process. Follicular parameters showed that Co-PMSCs better support in vitro growth and development of ovarian follicles than the other groups. The eccentric rate and estradiol production were statistically higher for the Co-PMSCs group than for the CM-PMSCs and control groups. Although the culture of early preantral follicles on DMPM and CM-PMSCs could improve in vitro follicular growth, co-culture of follicles with PMSCs showed even greater improvements in terms of follicular growth and diameter.

Printing 3D vagina tissue analogues with vagina decellularized extracellular matrix bioink

A variety of factors can cause vaginal loss. The patients are suffering from great psychological and physical pain, and there is an urgent need for vagina reconstruction. 3D-bioprinting is expected to achieve vaginal morphological restoration and true functional reconstruction. The current study aimed to explore the biomimetic 3D vagina tissue printing with acellular vagina matrix (AVM) bioink. The AVM from pig was converted to bioink by 15% gelatin and 3% sodium alginate mixed with the AVM solution. Rheology, scanning electron microscopy and HE staining were performed to characterize the bioink's viscosity, morphologies and biocompatibility. After printing, the viability of bone marrow mesenchymal stem cells (BMSCs) in the printed 3D scaffolds in vitro was investigated by a live/dead assay kit. Then, subcutaneous transplantation in rats were divided randomly into 3D scaffold group and 3D scaffold encapsulating CM-Dil-labeled BMSCs group. The results of HE, immunohistochemistry and immunofluorescence staining revealed that 3D scaffold encapsulating BMSCs expressed significant effects on the vascularization and epithelization of the printed vagina tissue, and the BMSCs could acquire the phenotype of vaginal epithelial cells and endothelial-like cells. The work showed that the biomimetic 3D vagina tissue with AVM bioink encapsulating BMSCs is a promising approach for vagina reconstruction.

Animal Models and Alternatives in Vaginal Research: a Comparative Review

While developments in gynecologic health research continue advancing, relatively few groups specifically focus on vaginal tissue research for areas like wound healing, device development, and/or drug toxicity. Currently, there is no standardized animal or tissue model that mimics the full complexity of the human vagina. Certain practical factors such as appropriate size and anatomy, costs, and tissue environment vary across species and moreover fail to emulate all aspects of the human vagina. Thus, investigators are tasked with compromising specific properties of the vaginal environment as it relates to human physiology to suit their particular scientific question. Our review aims to facilitate the appropriate selection of a model aptly addressing a particular study by discussing pertinent vaginal characteristics of conventional animal and tissue models. In this review, we first cover common laboratory animals studied in vaginal research-mouse, rat, rabbit, minipig, and sheep-as well as human, with respect to the estrus cycle and related hormones, basic reproductive anatomy, the composition of vaginal layers, developmental epithelial origin, and microflora. In light of these relevant comparative metrics, we discuss potential selection criteria for choosing an appropriate animal vaginal model. Finally, we allude to the exciting prospects of increasing biomimicry for in vitro applications to provide a framework for investigators to model, interpret, and predict human vaginal health.

Creation of a Bioengineered Ovary: Isolation of Female Germline Stem Cells for the Repopulation of a Decellularized Ovarian Bioscaffold

Ovarian failure is the most common cause of infertility and affects about 1% of young women. One innovative strategy to restore ovarian function may be represented by the development of a bioprosthetic ovary, obtained through the combination of tissue engineering and regenerative medicine.We here describe the two main steps required for bioengineering the ovary and for its ex vivo functional reassembling. The first step aims at producing a 3D bioscaffold, which mimics the natural ovarian milieu in vitro. This is obtained with a whole organ decellularization technique that allows the maintenance of microarchitecture and biological signals of the original tissue. The second step involves the use of magnetic activated cell sorting (MACS) to isolate purified female germline stem cells (FGSCs). These cells are able to differentiate in ovarian adult mature cells, when subjected to specific stimuli, and can be used them to repopulate ovarian decellularized bioscaffolds. The combination of the two techniques represents a powerful tool for in vitro recreation of a bioengineered ovary that may constitute a promising solution for hormone and fertility function restoring. In addition, the procedures here described allow for the creation of a suitable 3D platform with useful applications both in toxicological and transplantation studies.

A stereological study of 3D printed tissues engineered from rat vaginas

Background

This study aims to retrieve the stereological data from rat vaginas for 3D printing tissue-engineered vaginas.

Methods

In this study, five female Sprague-Dawley rats, aged 8–12 weeks, were used to obtaining the vagina tissues. Each vagina was divided into eight segments fixed in 4% paraformaldehyde and embedded in paraffin, whose two consecutive sections of each block were stained using hematoxylin and eosin (H&E) and anti-α-actin antibody with immunohistochemistry staining, respectively. The thickness of the epithelium, lamina propria, the smooth muscle layer, and the adventitia layer are measured. Then, the volume density of the epithelial cells and smooth muscle cells are counted using design-based stereology.

Results

The length and width of the rat vaginas were 2 and 1.5 cm, respectively. The thickness of the epithelium, lamina, propria, and adventitia layer was measured, and no significant difference was observed. However, the thickness of the smooth muscle layer was significantly different among these eight segments. The smooth muscle layer of the lower vagina is thicker than the upper vagina. The average volume density of epithelial cells and smooth muscle cells is 1.61×10⁹/cm³ and 5.38×10⁸/cm³. There was a significant difference observed.

Conclusions

We had successfully retrieved the stereological data of the vaginas. The gained data will supply us with the information for 3D printing vaginas and new insights into the structure of the vagina.

Whole-ovary decellularization generates an effective 3D bioscaffold for ovarian bioengineering

PURPOSE

To develop a new protocol for whole-ovary decellularization for the production of a 3D bioscaffold suitable for in vitro/ex vivo studies and for the reconstruction of a bioengineered ovary.

METHODS

Porcine ovaries were subjected to the decellularization process (DECELL; n = 20) that involved a freeze-thaw cycle, followed by sequential incubations in 0.5% SDS for 3 h, 1% Triton X-100 for 9 h, and 2% deoxycholate for 12 h. Untreated ovaries were used as a control (CTR; n = 6). Both groups were analyzed to evaluate cell and DNA removal as well as ECM preservation. DECELL bioscaffolds were assessed for cytotoxicity and cell homing ability.

RESULTS

DECELL ovaries maintained shape and homogeneity without any deformation, while their color turned from red to white. Histological staining and DNA quantification confirmed a decrease of 98.11% in DNA content, compared with the native tissue (CTR). Histochemical assessments demonstrated the preservation of intact ECM microarchitecture after the decellularization process. This was also confirmed by quantitative analysis of collagen, elastin, and GAG contents. DECELL bioscaffold showed no cytotoxic effects in co-culture and, when re-seeded with homologous fibroblasts, encouraged a rapid cell adhesion and migration, with repopulating cells increasing in number and aggregating in cluster-like structures, consistent with its ability to sustain cell adherence, proliferation, and differentiation.

CONCLUSION

The protocol described allows for the generation of a 3D bioscaffold that may constitute a suitable model for ex vivo culture of ovarian cells and follicles, as well as a promising tool for the reconstruction of a bioengineered ovary.

Prevascularized Tissue-Engineered Human Vaginal Mucosa: In Vitro Optimization and In Vivo Validation

Tissue engineering offers novel therapies for vaginal reconstruction in patients with congenital vaginal agenesis such as Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome. This study aims to reconstruct a prevascularized tissue-engineered model of human vaginal mucosa (HVM) using the self-assembly approach, free of exogenous materials. In this study, a new cell culture method was used to enhance microcapillary network formation while maintaining sufficient biomechanical properties for surgical manipulation. Human vaginal fibroblasts were coseeded with human umbilical vein endothelial cells (HUVECs). Transduction of HUVEC with a vector that allows the expression of both green fluorescent protein (GFP) and luciferase allowed the monitoring of the formation of a microvascular network in vitro and the assessment of the viability and stability of HUVEC in vivo. Two reconstructed vaginal mucosa grafts, a prevascularized, and a nonvascularized control were implanted subcutaneously on the back of 12 female nude mice and monitored for up to 21 days. Prevascularized grafts demonstrated signs of earlier vascularization compared with controls. However, there were no differences in graft survival outcomes in both groups. The finding of mouse red blood cells within GFP-positive capillaries 1 week after implantation demonstrates the capacity of the reconstructed capillary-like network to connect to the host circulation and sustain blood perfusion in vivo. Furthermore, sites of inosculation between GFP-positive HUVEC and mouse endothelial cells were observed within prevascularized grafts. Our results demonstrate that the addition of endothelial cells using a hybrid approach of self-assembly and reseeding generates a mature capillary-like network that has the potential to become functional in vivo, offering an optimized prevascularized HVM model for further translational research. Impact statement This study introduces a prevascularized tissue-engineered model of human vaginal mucosa (HVM), which is adapted for surgical applications. The prevascularization of tissue-engineered grafts aims to enhance graft survival and is an interesting feature for sexual function. Various scaffold-free cell culture methods were tested to reconstruct a mature microcapillary network within HVM grafts while meeting biomechanical needs for surgery. Moreover, this animal study assesses the vascular functionality of prevascularized grafts in vivo, serving as a proof of concept for further translational applications. This research underlines the continuous efforts to optimize current models to closely mimic native tissues and further improve surgical outcomes.

Application of Acellular Tissue Matrix for Enhancement of Weak Abdominal Wall in Animal Model

Background

Abdominal wall weakness occurs when the strength of muscle decreases due to physiological reason or iatrogenic injury. However, the treatment of this disease is complicated.

Aim

To study the therapeutic effect of acellular tissue matrix (ACTM), compared with the polypropylene mesh.

Methods

An abdominal wall weakness model was established in rabbits through motor nerves cutting. The polypropylene mesh and ACTM were implanted in the left and right abdomen sides, respectively. Mechanical testing of abdominal wall muscle and histology and scanning electron microscopy (SEM) evaluation of abdominal tissue explants were performed.

Results

In animal model establishment, the abdominal length of healthy and weakened abdominal wall was 17.0 ± 0.7 cm and 19.0 ± 1.2 cm, respectively (P=0.022), and the weak abdominal wall group showed a significant decrease of 1.116 ± 0.221 MPa in tensile stress (P=0.022), and the weak abdominal wall group showed a significant decrease of 1.116 ± 0.221 MPa in tensile stress (P=0.022), and the weak abdominal wall group showed a significant decrease of 1.116 ± 0.221 MPa in tensile stress (P=0.022), and the weak abdominal wall group showed a significant decrease of 1.116 ± 0.221 MPa in tensile stress (P=0.022), and the weak abdominal wall group showed a significant decrease of 1.116 ± 0.221 MPa in tensile stress (P=0.022), and the weak abdominal wall group showed a significant decrease of 1.116 ± 0.221 MPa in tensile stress (P=0.022), and the weak abdominal wall group showed a significant decrease of 1.116 ± 0.221 MPa in tensile stress (

Conclusion

The abdominal wall weakness model in rabbits was successfully established. ACTM is a promising biological material to be possibly further applied in clinical surgery in patients with abdominal wall weakness.

Evaluating two ovarian decellularization methods in three species

Since there is dearth of practical ways to obtain mature follicles from cryopreserved or native ovarian tissues, especially in patients suffering from ovarian dysfunction, tissue engineering may help in restoring ovarian function and/or fertility. In the present study, the effects of sodium dodecyl sulfate (SDS) and sodium hydroxide (NaOH) on the decellularization of ovarian tissues were studied in order to ascertain their suitability in creating suitable bioscaffolds. Cells were removed from the ovarian tissues of mouse, sheep and human. The samples were distributed among three groups, viz., control (not treated), SDS and NaOH treated. Qualitative histological evaluations, quantitative assessments (nuclear contents, collagen and glycosaminoglycan), immunohistochemistry staining (for laminin, fibronectin and Collagen I), cell viability and scanning electron microscopic (SEM) assays were performed for all experimental groups. Finally, suspensions of mouse ovarian cells were injected into human NaOH treated scaffolds and subsequently auto-transplanted to ovariectomized mice. H&E and IHC staining (GDF-9) were performed on human recellularized NaOH treated scaffolds 1 month after auto-transplantation. Although histological studies and quantitative evaluations confirmed the successful decellularization and presence of key factors in ovarian scaffolds under both treatment methods, NaOH showed more interesting outcomes. Cell metabolic activity in sheep and human ovaries treated with NaOH was statistically (p < 0.05) higher than for SDS treated samples after 72 h. Moreover, spherical associations with cuboidal cells in human NaOH treated scaffolds were observed and this follicular reconstruction was also confirmed by GDF-9. NaOH was found to be more suitable than SDS for the decellularization of ovarian tissues and it supports follicular reconstruction better than SDS. This is a valuable finding in tissue engineering research and can help in the creation of appropriate ovarian bioscaffolds.

Cultivated Human Vaginal Microbiome Communities Impact Zika and Herpes Simplex Virus Replication in ex vivo Vaginal Mucosal Cultures

The human vaginal microbiome (VMB) is a complex bacterial community that interacts closely with vaginal epithelial cells (VECs) impacting the mucosal phenotype and its responses to pathogenic insults. The VMB and VEC relationship includes nutrient exchange and regulation of signaling molecules that controls numerous host functions and defends against invading pathogens. To better understand infection and replication of sexually transmitted viral pathogens in the human vaginal mucosa we used our ex vivo VEC multilayer culture system. We tested the hypothesis that selected VMB communities could be identified that alter the replication of sexually transmitted viruses consistent with reported clinical associations. Sterile VEC multilayer cultures or those colonized with VMB dominated by specific Lactobacillus spp., or VMB lacking lactobacilli, were infected with Zika virus, (ZIKV) a single stranded RNA virus, or Herpes Simplex Virus type 2 (HSV-2), a double stranded DNA virus. The virus was added to the apical surface of the cultured VEC multilayer to model transmission during vaginal intercourse. Viral replication was measured 48 h later by qPCR. The results indicated that VEC cultures colonized by VMB containing Staphylococcus spp., previously reported as inflammatory, significantly reduced the quantity of viral genomes produced by ZIKV. HSV-2 titers were decreased by nearly every VMB tested relative to the sterile control, although Lactobacillus spp.-dominated VMBs caused the greatest reduction in HSV-2 titer consistent with clinical observations. To explore the mechanism for reduced ZIKV titers, we investigated inflammation created by ZIKV infection, VMB colonization or pre-exposure to selected TLR agonists. Finally, expression levels of human beta defensins 1–3 were quantified in cultures infected by ZIKV and those colonized by VMBs that impacted ZIKV titers. Human beta defensins 1–3 produced by the VEC showed no association with ZIKV titers. The data presented expands the utility of this ex vivo model system providing controlled and reproducible methods to study the VMB impact on STIs and indicated an association between viral replication and specific bacterial species within the VMB.

Porous poly-l-lactide-co-ɛ-caprolactone scaffold: a novel biomaterial for vaginal tissue engineering

The surgical reconstruction of functional neovagina is challenging and susceptible to complications. Therefore, developing tissue engineering-based treatment methods for vaginal defects is important. Our aim was to develop and test a novel supercritical carbon dioxide foamed poly-l-lactide-co-ɛ-caprolactone (scPLCL) scaffold for vaginal reconstruction. The scaffolds were manufactured and characterized for porosity (65 ± 4%), pore size (350 ± 150 µm) and elastic modulus (2.8 ± 0.4 MPa). Vaginal epithelial (EC) and stromal cells (SC) were isolated, expanded and characterized with flow cytometry. Finally, cells were cultured with scPLCL scaffolds in separate and/or co-cultures. Their attachment, viability, proliferation and phenotype were analysed. Both cell types strongly expressed cell surface markers CD44, CD73 and CD166. Strong expression of CD326 was detected with ECs and CD90 and CD105 with SCs. Both ECs and SCs attached and maintained viability on scPLCL. Further, scPLCL supported the proliferation of especially ECs, which also maintained epithelial phenotype (cytokeratin expression) during 14-day assessment period. Interestingly, ECs expressed uroplakin (UP) Ia, UPIb and UPIII markers; further, UPIa and UPIII expression was significantly higher on ECs cultured on scPLCL than on cell culture plastic. In conclusion, the scPLCL is potential scaffold for vaginal tissue engineering and the results of this study further illustrate the excellent biocompatibility of PLCL.

Porous poly-l-lactide-co-ɛ-caprolactone scaffold: a novel biomaterial for vaginal tissue engineering

The surgical reconstruction of functional neovagina is challenging and susceptible to complications. Therefore, developing tissue engineering-based treatment methods for vaginal defects is important. Our aim was to develop and test a novel supercritical carbon dioxide foamed poly-l-lactide-co-ɛ-caprolactone (scPLCL) scaffold for vaginal reconstruction. The scaffolds were manufactured and characterized for porosity (65 ± 4%), pore size (350 ± 150 µm) and elastic modulus (2.8 ± 0.4 MPa). Vaginal epithelial (EC) and stromal cells (SC) were isolated, expanded and characterized with flow cytometry. Finally, cells were cultured with scPLCL scaffolds in separate and/or co-cultures. Their attachment, viability, proliferation and phenotype were analysed. Both cell types strongly expressed cell surface markers CD44, CD73 and CD166. Strong expression of CD326 was detected with ECs and CD90 and CD105 with SCs. Both ECs and SCs attached and maintained viability on scPLCL. Further, scPLCL supported the proliferation of especially ECs, which also maintained epithelial phenotype (cytokeratin expression) during 14-day assessment period. Interestingly, ECs expressed uroplakin (UP) Ia, UPIb and UPIII markers; further, UPIa and UPIII expression was significantly higher on ECs cultured on scPLCL than on cell culture plastic. In conclusion, the scPLCL is potential scaffold for vaginal tissue engineering and the results of this study further illustrate the excellent biocompatibility of PLCL.