3D Bioprinted Alginate-Gelatin-Collagen Based Hydrogels Laden With Fibroblast and Keratinocyte Cells Show Potential for Regeneration of Injured Skin.

Bioactive scaffolds that mimic the skin's extracellular matrix are of current scientific interest. This study developed composite biopolymer-based bioprinted scaffolds laden with human dermal fibroblasts (HDFs) and primary epidermal keratinocytes (KCs) to generate constructs that can take active part in skin regeneration. Sodium alginate (ALG) was partially crosslinked with CaCl2 and combined with gelatin (GEL) and collagen (COL) to obtain composite bioinks for easy extrusion. CaCl2 concentration (0.2-4.5% w/v) and bioink physico-chemical properties were optimized using rheometry and scaffolds' stability was optimized through degradation studies. Cell viability within the printed scaffolds were evaluated (7 days) using MTT and live-dead assays, while the stratified layers of HDFs/KCs within the scaffolds were confirmed through immunofluorescence imaging. Bioinks partially crosslinked with 0.5% w/v CaCl2 allowed optimal extrusion during bioprinting, while scaffolds fully crosslinked with 1.5% w/v CaCl2 produced scaffolds that maintained their structural integrity and cell viability with appropriate proliferation and migration over the 7 days. This is the first study comprising ALG-GEL-COL, laden with HDFs and KCs and bioprinted for potential skin regeneration applications following injury. The generated bioprinted scaffolds will help advance the field of tissue regeneration, including potential to use as therapeutic drug delivery platform in future studies.