Recent advances in developing 3D culture systems of spermatogonial stem cell preservation and differentiation: A narrative review.

Male infertility has received vast attention in recent years and has no clear etiology in almost 40% of cases. Several methods have been suggested for preserving sperm and spermatogonial stem cells (SSCs) in both in vivo and in vitro conditions. The efficacy of these methods is related to their abilities, including providing an optimal environment for sperm preservation and long-term SSC culture for in vivo and in vitro differentiation of these cells. In this review article, a full MEDLINE/PubMed search was performed using the following search terms: "Spermatogonial Progenitor Cells, Stem Cells, Fertility Preservations, Sperm Freezing, Cell Differentiations, Tissue Scaffold, 3-Dimensional Cell Culture", which retrieved results from 1973-2022. Related articles were added to the bibliography of selected articles. Exclusion criteria included non-English language, abstract only, and unrelated articles. The production of functioning male germ cells is suggested by introducing modern bioengineered systems as a new hope for the maintenance of male fertility. Till now, few in vitro spermatogenesis investigations have provided appreciable amounts of mature gametes. Each method had benefits and disadvantages, but the 3-dimensional culture method had the greatest impact on the differentiation and preservation of SSCs. One of the critical elements of research is the preservation of sperm and the differentiation of SSCs. Several methods have been employed in this area. Various scaffolds providing an environment similar to an extracellular matrix and conditions for germ cell development and survival have been employed in recent research.

Recent advances and challenges in graphene-based nanocomposite scaffolds for tissue engineering application.

Graphene-based nanocomposites have recently attracted increasing attention in tissue engineering because of their extraordinary features. These biocompatible substances, in the presence of an apt microenvironment, can stimulate and sustain the growth and differentiation of stem cells into different lineages. This review discusses the characteristics of graphene and its derivatives, such as their excellent electrical signal transduction, carrier mobility, outstanding mechanical strength with improving surface characteristics, self-lubrication, antiwear properties, enormous specific surface area, and ease of functional group modification. Moreover, safety issues in the application of graphene and its derivatives in terms of biocompatibility, toxicity, and interaction with immune cells are discussed. We also describe the applicability of graphene-based nanocomposites in tissue healing and organ regeneration, particularly in the bone, cartilage, teeth, neurons, heart, skeletal muscle, and skin. The impacts of special textural and structural characteristics of graphene-based nanomaterials on the regeneration of various tissues are highlighted. Finally, the present review gives some hints on future research for the transformation of these exciting materials in clinical studies.

Assessment of mesenchymal stem cell effect on foreign body response induced by intraperitoneally implanted alginate spheres.

Foreign body response to implanted hydrogels and consequently fibrotic overgrowth on implanted spheres will decrease in vivo performance of these biomaterials. Considering the previous reports related to the immune-privileged properties of mesenchymal stem cells (MSCs), we hypothesized that encapsulated human placenta-derived MSCs (HP-MSCs) will mitigate the foreign body response against alginate hydrogels. The HP-MSC-laden alginate hydrogel was cross-linked with a CaCl2 solution. Morphological and mechanical properties of alginate spheres were determined by scanning electron microscopy imaging, degradation, and swelling tests. The HP-MSC-laden alginate spheres or cell-free spheres were implanted into the peritoneal cavity of BALB/c mice. After intraperitoneal implantation of spheres into BALB/c mice over a period of 14 days, capsules were recovered and precapsular fibrotic tissue on their surfaces was investigated. Assessment of encapsulated HP-MSC viability using acridine orange/propidium iodide staining revealed that foreign body response against cell-laden hydrogel results in fibrous overgrowth on spheres and consequently leads to the HP-MSC necrosis. In spite of immunomodulatory effects of MSCs, the introduction of spheres into the body induces foreign body response that affects the viability of immuno-isolated HP-MSCs during 14-day posttransplant period. The presence of HP-MSCs within alginate hydrogel could not reduce the fibrotic overgrowth on spheres compared with cell-free spheres. Therefore, there is an essential need for hydrogels that mitigate the foreign body response as a key challenge in the development of tissue engineering and drug delivery technologies.

Optical fluorescence imaging with shortwave infrared light emitter nanomaterials for in vivo cell tracking in regenerative medicine.

In vivo tracking and monitoring of adoptive cell transfer has a distinct importance in cell-based therapy. There are many imaging modalities for in vivo monitoring of biodistribution, viability and effectiveness of transferred cells. Some of these procedures are not applicable in the human body because of low sensitivity and high possibility of tissue damages. Shortwave infrared region (SWIR) imaging is a relatively new technique by which deep biological tissues can be potentially visualized with high resolution at cellular level. Indeed, scanning of the electromagnetic spectrum (beyond 1000 nm) of SWIR has a great potential to increase sensitivity and resolution of in vivo imaging for various human tissues. In this review, molecular imaging modalities used for monitoring of biodistribution and fate of administered cells with focusing on the application of non-invasive optical imaging at shortwave infrared region are discussed in detail.

Association between increased expression of endothelial isoform of nitric oxide synthase in the human fallopian tube and tubal ectopic pregnancy.

BACKGROUND: Tubal ectopic pregnancy (tEP) is the most common type of extra-uterine pregnancy and the most common cause of maternal mortality. Nitric oxide (NO) is a molecule that incorporates in many physiological processes of female reproductive system. Recent studies have demonstrated the possible role of endothelial isoform of nitric oxide synthase (eNOS) enzyme in the regulation of many reproductive events that occur in the fallopian tube (FT). OBJECTIVE: The aim of this study was to evaluate the expression of eNOS in the FTs of women with tEP. MATERIALS AND METHODS: In this case-control study, a total number of 30FTs samples were obtained from three groups including: 10 FTs of women that bearing an EP, 10 FTs from the non-pregnant women at luteal phase of the menstrual cycle, and 10 FTs of healthy pregnant women (n=10). Samples were fixed in 10% buffered formalin and then were evaluated by immunohistochemistry. RESULTS: Localization of eNOS was seen in secretory and ciliated luminal epithelium and vascular endothelium of all groups. However, we did not observed the expression of eNOS in smooth muscle cells of all groups. Expression of eNOS in luminal epithelium of women with EP compared to non-pregnant women at luteal phase of menstrual cycle and healthy pregnant group showed statistically significant increase (p=0.00). Significant difference in expression of eNOS was not observed in luminal epithelium of FTs of women at luteal phase compared to healthy pregnant groups (p=0.78). CONCLUSION: This study indicates that changes in expression of eNOS in luminal epithelium of FT may lead to development of EP. This article extracted from M.Sc. thesis. (Leyla Fath Bayati).