Protective effects of acetyl-L-carnitine against serum and glucose deprivation-induced apoptosis in rat adipose-derived mesenchymal stem cells

Characterization and biocompatibility evaluation of acellular rat skin scaffolds for skin tissue engineering applications

Utilization of acellular scaffolds, extracellular matrix (ECM) without cell content, is growing in tissue engineering, due to their high biocompatibility, bioactivity ad mechanical support. Hence, the purpose of this research was to study the characteristics and biocompatibility of decellularized rat skin scaffolds using the osmotic shock method. First, the skin of male Wistar rats was harvested and cut into 1 × 1 cm2 pieces. Then, some of the harvested parts were subjected to the decellularization process by applying osmotic shock. Comparison of control and scaffold samples was conducted in order to assure cell elimination and ECM conservation by means of histological evaluations, quantification of biochemical factors, measurement of DNA amount, and photographing the ultrastructure of the samples by scanning electron microscopy (SEM). In order to evaluate stem cell viability and adhesion to the scaffold, adipose-derived mesenchymal stem cells (AD-MSCs) were seeded on the acellular scaffolds. Subsequently, MTT test and SEM imaging of the scaffolds containing cultured cells were applied. The findings indicated that in the decellularized scaffolds prepared by osmotic shock method, not only the cell content was removed, but also the ECM components and its ultrastructure were preserved. Also, the 99% viability and adhesion of AD-MSCs cultured on the scaffolds indicate the biocompatibility of the decellularized skin scaffold. In conclusion, decellularized rat skin scaffolds are biocompatible and appropriate scaffolds for future investigations of tissue engineering applications.

Regulation of proliferation, apoptosis, hormone secretion and gene expression by acetyl-L-carnitine in yak (Bos grunniens) granulosa cells

Supplementation with acetyl-l-carnitine (ALC) during in vitro maturation significantly improves the rates of oocyte cleavage and morula and blastocyst formation in sheep and buffalo; however, the mode of action of ALC in improving oocyte competence is not completely understood. Therefore, the aim of this study was to investigate the effects of ALC on proliferation, antioxidant properties, lipid droplet accumulation and steroid hormone secretion in yak (Bos grunniens) granulosa cells (GCs). Yak GCs were identified using FSHR immunofluorescence. The cells were treated with different concentrations of ALC, cell proliferation was detected by cell counting kit-8, and the optimal concentration and treatment time were determined for subsequent experiments. Then, reactive oxygen species (ROS) were detected by a DCFH-DA probe, and lipid droplet accumulation was observed by oil red O staining. Estradiol (E2) and progesterone (P4) in the medium were detected by ELISA, and the expression of genes related to cell proliferation, apoptosis, the cell cycle, antioxidants and steroid synthesis was determined by RT‒qPCR. The results showed that 1 mM ALC treatment for 48 h was the optimum treatment. It significantly increased cell viability (P < 0.05), significantly decreased the amount of ROS and lipid droplet content, and promoted P4 and E2 secretion (P < 0.05) of yak GCs. RT‒qPCR results verified that GCs treated with 1 mM ALC for 48 h significantly increased the expression of genes related to anti-apoptosis and the cell cycle (BCL-2, PCNA, CCND1 and CCNB1), antioxidants (CAT, SOD2 and GPX1), and E2 and P4 secretion (StAR, CYP19A1 and HSD3B1) (P < 0.05), but it significantly decreased the expression of apoptosis genes (BAX and P53) (P < 0.05). In conclusion, ALC increased the viability of yak GCs, reduced the amount of ROS and lipid droplets, increased P4 and E2 synthesis and affected the expression of related genes in yak GCs.

Hypoxia-induced CCL2/CCR2 axis in adipose-derived stem cells (ADSCs) promotes angiogenesis by human dermal microvascular endothelial cells (HDMECs) in flap tissues

Flap expansion has become an important method widely used in wound repair and organ reconstruction. However, distal skin flap ischemic necrosis remains a problematic complication. In this study, integrative bioinformatics analyses indicated the upregulation of C-C motif chemokine ligand 2 (CCL2) and C-C motif chemokine receptor 2 (CCR2) in reperfusion-exposed skin flap tissues. In adipose-derived stem cells (ADSCs, CD90-positive, CD29-positive, CD34-negative, and CD106-negative) exposed to hypoxia, HIF-1α and CCL2 levels were significantly elevated. Conditioned medium (CM) from hypoxia-stimulated ADSCs promoted HDMEC proliferation, migration, and tube formation, partially inhibited by sh-CCL2-induced CCL2 knockdown or neutralized antibody-induced CCL2 depletion in ADSCs. Consistently, CCL2, CCR2, TNF-α, TLR2, and TLR4 protein levels in HDMECs were significantly increased by hypoxia-treated ADSCs CM, and partially decreased by sh-CCL2-induced CCL2 knockdown or neutralizing antibody-induced CCL2 knockdown in ADSCs. In the flap expansion model, ADSCs transplantation significantly improved flap survival and angiogenesis by endothelial cells in flap tissues, whereas CCL2 knockdown in ADSCs partially eliminated the improvement by ADSCs transplantation; overexpression of CCL2 in ADSCs further promoted the effects of ADSCs transplantation on skin flap. In conclusion, the CCL2/CCR2 axis in ADSCs could be induced by hypoxia, promoting HDMEC proliferation, migration, and tube formation and improving flap survival and angiogenesis in flap tissues.

The Influence of Intervertebral Disc Microenvironment on the Biological Behavior of Engrafted Mesenchymal Stem Cells

Intervertebral disc degeneration is the main cause of low back pain. Traditional treatment methods cannot repair degenerated intervertebral disc tissue. The emergence of stem cell therapy makes it possible to regenerate and repair degenerated intervertebral disc tissue. At present, mesenchymal stem cells are the most studied, and different types of mesenchymal stem cells have their own characteristics. However, due to the harsh and complex internal microenvironment of the intervertebral disc, it will affect the biological behaviors of the implanted mesenchymal stem cells, such as viability, proliferation, migration, and chondrogenic differentiation, thereby affecting the therapeutic effect. This review is aimed at summarizing the influence of each intervertebral disc microenvironmental factor on the biological behavior of mesenchymal stem cells, so as to provide new ideas for using tissue engineering technology to assist stem cells to overcome the influence of the microenvironment in the future.

Acetyl l-carnitine protects adipose-derived stem cells against serum-starvation: regulation on the network composed of reactive oxygen species, autophagy, apoptosis and senescence

Adipose-derived stem cells (ADSCs) play an important role in cell therapy and regenerative medicine. However, local nutritional deficiency often limits therapeutical effect of the transplanted cells. Acetyl l-carnitine (ALC) is a common energy metabolism regulator and free radical scavenger. This study investigated the effect of ALC on ADSCs exposed to severe serum-deprivation and explored the relative machanisms. Treating with 1 mM ALC improved proliferation and alleviated senescence of starved cells, accompanied with reduced reactive oxygen species (ROS) and increased protein expression of SOD1 and catalase. In addition, ALC inhibited apoptosis but increased starvation-induced autophagy, which might be related to the regulation of phases of dissociation of Bcl-2-Beclin1 and Bcl-2-Bax complexes. Evidence obtained by replacing ALC with N-acetylcysteine (N-AC) suggested that ROS might be the central inducer of autophagy, apoptosis and senescence. There was a difference between ALC and N-AC in the protection mechanism, that was, compared with N-AC, ALC maintained autophagy well at the same time as anti-oxidation. Inhibition of autophagy by 3-methyladenine (3-MA) partially offset the protective effect of ALC. However, despite low-level ROS and enhanced autophagy, ALC with high concentration (10 mM) markedly aggravated cell apoptosis and senescence, thus losing cytoprotection and even causing damage.

Platelet extracellular vesicles enhance the proangiogenic potential of adipose-derived stem cells in vivo and in vitro

BACKGROUND

Adipose-derived mesenchymal stem cells (ADSC)-based therapy is an outstanding treatment strategy for ischaemic disease. However, the therapeutic efficacy of this strategy is not ideal due to the poor paracrine function and low survival rate of ADSCs in target regions. Platelet extracellular vesicles (PEVs) are nanoparticles derived from activated platelets that can participate in communication between cells. Accumulating evidence indicates that PEVs can regulate the biological functions of several cell lines. In the present study, we aimed to investigate whether PEVs can modulate the proangiogenic potential of ADSCs in vitro and in vivo.

METHODS

PEVs were identified using scanning electron microscope (SEM), flow cytometry (FCM) and nanoparticle tracking analysis (NTA). The CCK8 assay was performed to detect proliferation of cells. Transwell and wound healing assays were performed to verify migration capacity of cells. AnnexinV-FITC/PI apoptosis kit and live/dead assay were performed to assess ADSCs apoptosis under Cocl₂-induced hypoxia condition. The underlying mechanisms by which PEVs affected ADSCs were explored using real time-PCR(RT-PCR) and Western blot. In addition, matrigel plug assays were conducted and mouse hindlimb ischaemic models were established to investigate the proangiogenic potential of PEV-treated ADSCs in vivo.

RESULTS

We demonstrated that ADSC could internalize PEVs, which lead to a series of biological reactions. In vitro, dose-dependent effects of PEVs on ADSC proliferation, migration and antiapoptotic capacity were observed. Western blotting results suggested that multiple proteins such as ERK, AKT, FAK, Src and PLCγ1 kinase may contribute to these changes. Furthermore, PEVs induced upregulation of several growth factors expression in ADSCs and amplified the proliferation, migration and tube formation of HUVECs induced by ADSC conditioned medium (CM). In in vivo experiments, compared with control ADSCs, the injection of PEV-treated ADSCs resulted in more vascularization in matrigel plugs, attenuated tissue degeneration and increased blood flow and capillary density in ischaemic hindlimb tissues.

CONCLUSION

Our data demonstrated that PEVs could enhance the proangiogenic potential of ADSCs in mouse hindlimb ischaemia. The major mechanisms of this effect included the promotion of ADSC proliferation, migration, anti-apoptosis ability and paracrine secretion.

Role of sperm apoptosis and oxidative stress in male infertility: A narrative review

Activation of caspase, externalization of phosphatidyl serine, change in the mitochondrial membrane potential, and DNA fragmentation are apoptosis markers found in human ejaculated spermatozoa. Also, reactive oxygen species (ROS) play a vital role in the different types of male infertility. In this review, data sources including Google Scholar, Scopus, PubMed, and Science Direct were searched for publications with no particular time restriction to get a holistic and comprehensive view of the research. Apoptosis regulates the male germ cells, correct function and development from the early embryonic stages of gonadal differentiation to fertilization. In addition to maintaining a reasonable ratio between the Sertoli and germ cells, apoptosis is one of the well-known quality control mechanisms in the testis. Also, high ROS levels cause a heightened and dysregulated apoptotic response. Apoptosis is one of the well-known mechanisms of quality control in the testis. Nevertheless, increased apoptosis may have adverse effects on sperm production. Recent studies have shown that ROS and the consequent oxidative stress play a crucial role in apoptosis. This review aims to assimilate and summarize recent findings on the apoptosis in male reproduction and fertility. Also, this review discusses the update on the role of ROS in normal sperm function to guide future research in this area.