Improved Small Extracellular Vesicle Secretion of Rat Adipose-Derived Stem Cells by Microgrooved Substrates through Upregulation of the ESCRT-III-Associated Protein Alix.

Mesenchymal stem cell-derived small extracellular vesicles (MSC-sEVs) hold great potential for regenerative therapies and have received considerable research attention in recent years. However, the use of MSC-sEVs is limited by very low yield in routine culture conditions and suboptimal potency for certain diseases. Thus, strategies that enable the production of sufficient quantities of sEVs with desired therapeutic cargo in a facile and inexpensive way are in high demand. This study finds that the microgrooved substrates stimulate rat adipose-derived mesenchymal stem cells (rASCs) to produce a larger quantity of sEVs than the flat substrates. Further investigation suggests that the ESCRT-III-associated protein Alix may be involved in mediating the elevated sEV production of rASCs on the microgrooved substrates. Besides, the cargo of sEVs is altered. SEVs secreted by rASCs on the microgrooved substrates carry higher levels of proangiogenic miRNAs and growth factors than those secreted by rASCs on the flat substrates. Functional assessments demonstrate that sEVs from rASCs on microgrooved substrates enhance the angiogenic properties of Human umbilical vein endothelial cells. The findings demonstrate that substrate topography is an effective regulator of the sEVs secretion by rASCs and highlight the potential of using microgrooved substrates as a platform to produce rASC-sEVs rich in pro-angiogenic factors.