In situ forming injectable MSC-loaded GelMA hydrogels combined with PD for vascularized sweat gland regeneration

Dear Editor, Three dimensional (3D) bioprinted extracellular matrix (ECM) can be used to provide both biochemical and biophysical cues to direct mesenchymal stem cells (MSCs) differentiation, and then differentiated cells were isolated for implantation in vivo using surgical procedures. However, the reduced cell activity after cell isolation from 3D constructs and low cell retention in injured sites limit its application[1]. Methacrylated gelatin (GelMA) hydrogel has the advantage of fast crosslinking, which could resemble complex architectures of tissue construct in vivo[2]. Here, we adopted a noninvasive bioprinting procedure to imitate the regenerative microenvironment that could simultaneously direct the sweat gland (SG) and vascular differentiation from MSCs and ultimately promote the replacement of glandular tissue in situ (Fig. 1a).