Autophagy is a highly conserved cellular process that degrades modified, surplus, or harmful cytoplasmic components by sequestering them in autophagosomes which then fuses with the lysosome for degradation. As a major intracellular degradation and recycling pathway, autophagy is crucial for maintaining cellular homeostasis, as well as for remodeling during normal development. Impairment of this process has been implicated in various diseases, in the pathogenic response to bacterial and viral infections, and in aging. Pluripotent stem cells, with their ability to self-replicate and to give rise to any specialized cell type, are very valuable resources for cell-based medical therapies and open a number of promising avenues for studying human development and disease. It has been suggested that autophagy is vital for the maintenance of cellular homeostasis in stem cells, and subsequently more in-depth knowledge about the regulation of autophagy in stem cell biology has been acquired recently. In this review, we describe the most significant advances in the understanding of autophagy regulation in hematopoietic and mesenchymal stem cells, as well as in induced pluripotent stem cells. In particular, we highlight the roles of various autophagy activities in the regulation of self-renewal and differentiation of these stem cells.

BackgroundHypertrophic scars cause cosmetic and functional problems for patients, and their treatment remains challenging. Mechanical micronization of adipose tissue can remove adipocytes and concentrate functional cells. Stromal vascular fraction (SVF)-gel is obtained by a series of simple mechanical processes, including shifting between syringes and centrifugation. This study aimed to assess the therapeutic effect of SVF-gel on hypertrophic scars.MethodsA model of hypertrophic scars was established in rabbit ears. SVF-gel and SVF cells were obtained from rabbit inguinal fat pads and injected into scars. Phosphate-buffered saline (PBS) was used as a control. Scars were structurally characterized by histologic and immunohistochemical analyses. Expression of inflammatory and fibrogenic genes was evaluated.ResultsHypertrophic scars became less visible and softer following injection of SVF-gel or SVF cells. Dermal thickness was significantly lower in the groups treated with SVF-gel and SVF cells than in the PBS-treated group. Treatment with SVF-gel restored subcutaneous fat tissue in scars, while treatment with SVF cells and PBS did not. Injection of SVF-gel and SVF cells reduced macrophage infiltration in the dermal layer and decreased mRNA expression of interleukin-6 and monocyte chemoattractant protein-1. In addition, the level of myofibroblasts and collagen deposition were reduced in the groups treated with SVF-gel and SVF cells.ConclusionsSVF-gel has therapeutic effects on hypertrophic scars. Injection of SVF-gel into hypertrophic scars restores subcutaneous fat tissue and reduces the levels of macrophages and myofibroblasts; thus, it decreased the dermal thickness of the scar.

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