Tissue engineering of mouse uterus using menstrual blood stem cells (MenSCs) and decellularized uterine scaffold

Region-Specific Decellularization of Porcine Uterine Tube Extracellular Matrix: A New Approach for Reproductive Tissue-Engineering Applications

The uterine tube extracellular matrix is a key component that regulates tubal tissue physiology, and it has a region-specific structural distribution, which is directly associated to its functions. Considering this, the application of biological matrices in culture systems is an interesting strategy to develop biomimetic tubal microenvironments and enhance their complexity. However, there are no established protocols to produce tubal biological matrices that consider the organ morphophysiology for such applications. Therefore, this study aimed to establish region-specific protocols to obtain decellularized scaffolds derived from porcine infundibulum, ampulla, and isthmus to provide suitable sources of biomaterials for tissue-engineering approaches. Porcine uterine tubes were decellularized in solutions of 0.1% SDS and 0.5% Triton X-100. The decellularization efficiency was evaluated by DAPI staining and DNA quantification. We analyzed the ECM composition and structure by optical and scanning electronic microscopy, FTIR, and Raman spectroscopy. DNA and DAPI assays validated the decellularization, presenting a significative reduction in cellular content. Structural and spectroscopy analyses revealed that the produced scaffolds remained well structured and with the ECM composition preserved. YS and HEK293 cells were used to attest cytocompatibility, allowing high cell viability rates and successful interaction with the scaffolds. These results suggest that such matrices are applicable for future biotechnological approaches in the reproductive field.

Current status and challenges in uterine myometrial tissue engineering

The uterus undergoes significant modifications throughout pregnancy to support embryo development and fetal growth. However, conditions like fibroids, adenomyosis, cysts, and C-section scarring can cause myometrial damage. The importance of the uterus and the challenges associated with myometrial damage, and the need for alternative approaches are discussed in this review. The review also explores the recent studies in tissue engineering, which involve principles of combining cells, scaffolds, and signaling molecules to create functional uterine tissues. It focuses on two key approaches in uterine tissue engineering: scaffold technique using decellularized, natural, and synthetic polymer and 3D bioprinting. These techniques create supportive structures for cell growth and tissue formation. Current treatment options for myometrial damage have limitations, leading to the exploration of regenerative medicine and integrative therapies. The review emphasizes the potential benefits of tissue engineering, including more effective and less invasive treatment options for myometrial damage. The challenges of developing biocompatible materials and optimizing cell growth and differentiation are discussed. In conclusion, uterine tissue engineering holds promise for myometrial regeneration and the treatment of related conditions. This review highlights the scientific advancements in the field and underscores the potential of tissue engineering as a viable approach. By addressing the limitations of current treatments, tissue engineering offers new possibilities for improving reproductive health and restoring uterine functionality. Future research shall focus on overcoming challenges and refining tissue engineering strategies to advance the field and provide effective solutions for myometrial damage and associated disorders.

The Decellularized Calf Testis: Introducing Suitable Scaffolds for Spermatogenesis Studies

BACKGROUND

Men's infertility and lack of production of healthy and active sperm are concerns of recent years in most countries. Studies on the preparation of extracellular matrix (ECM) from decellularization of testis tissue and spermatogenesis could provide proper results to solve some of the men's infertility problems. This study aims to decellularize calf testis by different methods to reach a suitable scaffold and introduce it in spermatogenesis studies.

MATERIALS AND METHODS

In this experimental study, calf testis were decellularized by a freeze-de freeze, 1% sodium deoxycholate (SD), 0.1% sodium dodecyl sulfate (SDS), 0.1% SDS-vacuum, 1% SDS, 1% SDS-vacuum, and Triton- X100 methods. The content of DNA, collagen, and glycosaminoglycan (GAG) was analyzed using the kit and staining with Hematoxylin-Eosin, Masson's trichrome, Alcian blue, and Orcein methods. The morphology of the scaffolds was analyzed with a scanning electron microscope (SEM).

RESULTS

Methods of 1% SDS, 1% SDS-vacuum, and 1% SD completely removed the cells. The preservation of collagen and GAG was confirmed using the staining kit and methods. The use of a vacuum showed greater porosity in the SEM images. Toxicity and hemolysis were not observed in the scaffolds.

CONCLUSION

Testis decellularization with 1% SDS and 1% SD, in addition to cell removal, could maintain the ECM structure to a large extent without having cytotoxic and hemolysis effects.

Current Status of Tissue Regenerative Engineering for the Treatment of Uterine Infertility

With the recent developments in tissue engineering, scientists have attempted to establish seed cells from different sources, create cell sheets through various technologies, implant them on scaffolds with various spatial structures, or load scaffolds with cytokines. These research results are very optimistic, bringing hope to the treatment of patients with uterine infertility. In this article, we reviewed articles related to the treatment of uterine infertility from the aspects of experimental treatment strategy, seed cells, scaffold application, and repair criteria so as to provide a basis for future research.

Perfusion and Ultrasonication Produce a Decellularized Porcine Whole-Ovary Scaffold with a Preserved Microarchitecture

The application of decellularized scaffolds for artificial tissue reconstruction has been an approach with great therapeutic potential in regenerative medicine. Recently, biomimetic ovarian tissue reconstruction was proposed to reestablish ovarian endocrine functions. Despite many decellularization methods proposed, there is no established protocol for whole ovaries by detergent perfusion that is able to preserve tissue macro and microstructure with higher efficiency. This generated biomaterial may have the potential to be applied for other purposes beyond reproduction and be translated to other areas in the tissue engineering field. Therefore, this study aimed to establish and standardize a protocol for porcine ovaries' decellularization based on detergent perfusion and ultrasonication to obtain functional whole-ovary scaffolds. For that, porcine ovaries (n = 5) were perfused with detergents (0.5% SDS and 1% Triton X-100) and submitted to an ultrasonication bath to produce acellular scaffolds. The decellularization efficiency was evaluated by DAPI staining and total genomic DNA quantification. ECM morphological evaluation was performed by histological, immunohistochemistry, and ultrastructural analyses. ECM physico-chemical composition was evaluated using FTIR and Raman spectroscopy. A cytocompatibility and cell adhesion assay using murine fibroblasts was performed. Results showed that the proposed method was able to remove cellular components efficiently. There was no significant ECM component loss in relation to native tissue, and the scaffolds were cytocompatible and allowed cell attachment. In conclusion, the proposed decellularization protocol produced whole-ovaries scaffolds with preserved ECM composition and great potential for application in tissue engineering.

Fundamentals and Applications of Raman-Based Techniques for the Design and Development of Active Biomedical Materials

Raman spectroscopy is an analytical method based on light-matter interactions that can interrogate the vibrational modes of matter and provide representative molecular fingerprints. Mediated by its label-free, non-invasive nature, and high molecular specificity, Raman-based techniques have become ubiquitous tools for in situ characterization of materials. This review comprehensively describes the theoretical and practical background of Raman spectroscopy and its advanced variants. The numerous facets of material characterization that Raman scattering can reveal, including biomolecular identification, solid-to-solid phase transitions, and spatial mapping of biomolecular species in bioactive materials, are highlighted. The review illustrates the potential of these techniques in the context of active biomedical material design and development by highlighting representative studies from the literature. These studies cover the use of Raman spectroscopy for the characterization of both natural and synthetic biomaterials, including engineered tissue constructs, biopolymer systems, ceramics, and nanoparticle formulations, among others. To increase the accessibility and adoption of these techniques, the present review also provides the reader with practical recommendations on the integration of Raman techniques into the experimental laboratory toolbox. Finally, perspectives on how recent developments in plasmon- and coherently-enhanced Raman spectroscopy can propel Raman from underutilized to critical for biomaterial development are provided.

A Combination of Physical and Chemical Treatments Is More Effective in The Preparation of Acellular Uterine Scaffolds

OBJECTIVE

Decellularized uterine scaffold, as a new achievement in tissue engineering, enables recellularization and regeneration of uterine tissues and supports pregnancy in a fashion comparable to the intact uterus. The acellular methods are methods preferred in many respects due to their similarity to normal tissue, so it is necessary to try to introduce an acellularization protocol with minimum disadvantages and maximum advantages. Therefore, this study aimed to compare different protocols to achieve the optimal uterus decellularization method for future in vitro and in vivo bioengineering experiments.

MATERIALS AND METHODS

In this experimental study, rat uteri were decellularized by four different protocols (P) using sodium dodecyl sulfate (SDS), with different doses and time incubations (P1 and P2), SDS/Triton-X100 sequentially (P3), and a combination of physical (freeze/thaw) and chemical reagents (SDS/Triton X-100). The scaffolds were examined by histopathological staining, DNA quantification, MTT assay, blood compatibility assay, FESEM, and mechanical studies.

RESULTS

Histology assessment showed that only in P4, cell residues were completely removed. Masson's trichrome staining demonstrated that in P3, collagen fibers were decreased; however, no damage was observed in the collagen bundles using other protocols. In indirect MTT assays, cell viabilities achieved by all used protocols were significantly higher than the native samples. The percentage of red blood cell (RBC) hemolysis in the presence of prepared scaffolds from all 4 protocols was less than 2%. The mechanical properties of none of the obtained scaffolds were significantly different from the native sample except for P3.

CONCLUSION

Uteri decellularized with a combination of physical and chemical treatments (P4) was the most favorable treatment in our study with the complete removal of cell residue, preservation of the three-dimensional structure, complete removal of detergents, and preservation of the mechanical property of the scaffolds.

Enhancing Stem Cell-Based Therapeutic Potential by Combining Various Bioengineering Technologies

Stem cell-based therapeutics have gained tremendous attention in recent years due to their wide range of applications in various degenerative diseases, injuries, and other health-related conditions. Therapeutically effective bone marrow stem cells, cord blood- or adipose tissue-derived mesenchymal stem cells (MSCs), embryonic stem cells (ESCs), and more recently, induced pluripotent stem cells (iPSCs) have been widely reported in many preclinical and clinical studies with some promising results. However, these stem cell-only transplantation strategies are hindered by the harsh microenvironment, limited cell viability, and poor retention of transplanted cells at the sites of injury. In fact, a number of studies have reported that less than 5% of the transplanted cells are retained at the site of injury on the first day after transplantation, suggesting extremely low (<1%) viability of transplanted cells. In this context, 3D porous or fibrous national polymers (collagen, fibrin, hyaluronic acid, and chitosan)-based scaffold with appropriate mechanical features and biocompatibility can be used to overcome various limitations of stem cell-only transplantation by supporting their adhesion, survival, proliferation, and differentiation as well as providing elegant 3-dimensional (3D) tissue microenvironment. Therefore, stem cell-based tissue engineering using natural or synthetic biomimetics provides novel clinical and therapeutic opportunities for a number of degenerative diseases or tissue injury. Here, we summarized recent studies involving various types of stem cell-based tissue-engineering strategies for different degenerative diseases. We also reviewed recent studies for preclinical and clinical use of stem cell-based scaffolds and various optimization strategies.

An overview of post transplantation events of decellularized scaffolds

Regenerative medicine and tissue engineering are reasonable techniques for repairing failed tissues and could be a suitable alternative to organ transplantation. One of the most widely used methods for preparing bioscaffolds is the decellularization procedure. Although cell debris and DNA are removed from the decellularized tissues, important compositions of the extracellular matrix including proteins, proteoglycans, and glycoproteins are nearly preserved. Moreover, the obtained scaffolds have a 3-dimensional (3D) structure, appropriate naïve mechanical properties, and good biocompatibility. After transplantation, different types of host cells migrate to the decellularized tissues. Histological and immunohistochemical assessment of the different bioscaffolds after implantation reveals the migration of parenchymal cells, angiogenesis, as well as the invasion of inflammatory and giant foreign cells. In this review, the events after transplantation including angiogenesis, scaffold degradation, and the presence of immune and tissue-specific progenitor cells in the decellularized scaffolds in various hosts, are discussed.

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.

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.

Design and Characterization of Maltose-Conjugated Polycaprolactone Nanofibrous Scaffolds for Uterine Tissue Engineering

Purpose

Uterine anomalies are prevalent in women, and the major treatment assisted to them is hysterectomy as donor availability is extremely low. To overcome this, engineering uterine myometrium smooth muscle tissue has become very important. Several studies have shown that polycaprolactone (PCL) nanofibers are very effective in engineering smooth muscles, as this type of scaffold has structural similarities to the extracellular matrices of the cells. Here, we hypothesize that by electrospinning PCL nanofibers, they form a suitable scaffold for uterine tissue engineering.

Methods

Polycaprolactone nanofibrous scaffolds were fabricated, and surface modification was performed following two step wet chemistry method. First step is aminolysis which introduces the primary amine groups on the PCL scaffolds following which maltose is conjugated on the scaffolds. This was confirmed by the ninhydrin assay for the presence of amine groups. This was followed by ELLA assay where the presence of maltose on the scaffold was quantified. Modified scaffolds were further characterized by scanning electron microscope (SEM), contact angle analysis and Fourier transform infrared spectroscopy (FTIR). MTT assay, live-dead assay and actin staining were performed on the maltose immobilization to study the improvement of the cell attachment and proliferation rates on the modified scaffolds.

Results

Human uterine fibroblast (HUF) cells displayed significant proliferation on the maltose-modified PCL scaffolds, and they also exhibited appropriate morphology indicating that these modified fibers are highly suitable for uterine cell growth.

Conclusion

Our results indicate that the fabricated maltose PCL (MPCL) scaffolds would be a potential biomaterial to treat uterine injuries and promote regeneration.

Lay Summary and Future Work

Uterine anomalies are prevalent in women, and the major treatment is hysterectomy as donor availability is extremely low. Over the past few years, considerable efforts have been directed towards uterine tissue regeneration. This study is to design a tissue engineered scaffold that could act as a human uterine myometrial patch. We propose to create uterine fibroblast-based synthetic scaffolds that act in a condition similar to the intrauterine microenvironment where the embryos are embedded in the uterine wall. For understanding of the efficiency of the myometrial patch, functional characterization will be performed to study the effects of estrogen and prostaglandins on myometrial activity of the designed patch. Results from these experiments will assist a deeper understanding of how to construct a total bioengineered uterus which can substitute the uterus transplantation procedure, which nonetheless is in its initial stages of development.

Graphical Abstract