Transcriptome analysis in osteoarthritis primary tissues identifies high-confidence effector genes.

Damage to the testicles that affects sperm production is a major cause of male infertility. It can happen for several reasons, such as chemotherapy, toxins in the environment, infections, ischemia–reperfusion, and genetic defects [,,]. Alkylating agents like busulfan have been widely used as a reliable way to cause severe germ cell depletion and testicular dysfunction in experiments []. Busulfan specifically targets cells in the seminiferous epithelium that are dividing quickly, which depletes spermatogonial stem cells and then causes Sertoli and Leydig cells to impair their function []. The pathological features that result from this treatment are hypergonadotropic hypogonadism (high follicle-stimulating hormone (FSH)/luteinizing hormone (LH) and low testosterone), azoospermia or severe oligozoospermia, increased germ cell apoptosis, oxidative stress, and chronic inflammation. These pathological features recapitulate key aspects of in many types of non-obstructive spermatogenic impairment [,]. Currently, very few treatment options exist for these conditions, and none have been proven to restore endogenous spermatogenesis []. Cell-based regenerative strategies have gotten a lot of attention in the last few years. Researchers have looked at mesenchymal stem cells (MSCs) from bone marrow, fat tissue, and umbilical cord in animal models of testicular injury [,,]. For instance, giving MSCs through the veins or directly into the testicles has been shown to restore sperm production, improve hormone levels, and lower cell death in rodents that had been treated with busulfan []. The beneficial effects are mostly due to paracrine signaling, which includes the release of growth factors (like glial cell line-derived neurotrophic factor (GDNF), stem cell factor (SCF), and vascular endothelial growth factor (VEGF)), anti-inflammatory cytokines (like interleukin-10 (IL-10) and transforming growth factor-β (TGF-β)), and exosomes that change the local microenvironment and encourage the growth of stem cells in the body [,]. A recent review of the adipose-derived MSC secretome found that it helps seminiferous tubules grow back, lowers apoptosis, and speeds up the recovery of Leydig cells in testicular injury caused by chemicals []. However, there are a number of problems that MSC therapy will have to overcome to be used in people. To get enough MSCs, you often have to grow them outside of the body for several weeks, which delays treatment and raises costs [,]. Long-term culture can cause genetic instability and, in rare cases, tumorigenicity [,]. There are also ethical issues with using certain MSC sources, like fetal or embryonic tissues [,], that make them less useful, particularly due to concerns about consent and the moral implications of using these tissues in research and treatment. Researchers are looking for other cell types that are easy to get, safe, and work well because of these problems. The stromal vascular fraction (SVF) is a group of different types of cells that come from breaking down adipose tissue with enzymes, so there is no need to grow them in culture []. SVF is made up of a mix of endothelial progenitor cells, pericytes, macrophages, fibroblasts, and adipose-derived stem cells (ADSCs) []. The ADSCs in SVF are very similar to cultured MSCs in many ways, such as their ability to be multipotent and affect the immune system []. However, SVF can be made in just 2–3 h from a small lipoaspirate, which makes it a “point-of-care” regenerative tool []. A recent in-depth review found that SVF has both immunomodulatory and proangiogenic effects []. It does so by modulating both innate and adaptive immune cells and releasing pro-angiogenic factors like VEGF, hepatocyte growth factor (HGF), and platelet-derived growth factor (PDGF) []. Researchers have looked into how SVF can help treat a wide range of diseases, such as osteoarthritis, heart attacks, peripheral neuropathy, and tissue fibrosis caused by radiation [,]. In most cases, the beneficial effects happen through paracrine mechanisms instead of direct differentiation. This leads to less inflammation, more blood vessel growth, and tissue regeneration [,].