Preliminary study of in‐situ 3D bioprinted nano‐silicate biopolymer scaffolds for muscle repair in VML defects

Abstract

IntroductionThe traumatic or surgical loss of skeletal muscle with resultant functional impairment (volumetric muscle loss (VML)) is a challenging clinical problem. The current standard treatment care for VML is autologous tissue grafts and physical therapy, which still faces the challenge of donor site morbidity in large defect cases. 3D printing techniques for tissue engineering allows the precise control of micropatterning by determining the dimensions of filaments, the size and shape of pores and the percentage of porosity of the scaffold. Our hypothesis is using 3D printing of biopolymer‐nanosilicate scaffolds in‐situ will enhance muscle regeneration in VML defects.Materials and MethodsMethacrylated gelatin (MAG) biopolymer Laponite (Lp) nano‐silicate scaffolds were prepared as a bio‐ink using a solution‐precipitation process. Our study includes designing and optimization of 3D printing parameters for printing MAG‐Lp scaffolds and in‐vitro evaluation of cell viability (live‐dead), proliferation, and differentiation of mouse myoblast precursor cells on these scaffolds. We further analyzed the in‐situ (directly in the defect) 3D printing (using a robocaster) in a rat VML model in tibialis anterior muscle to evaluate the feasibility, precision, flexibility and attachment of the scaffold to the defect.ResultsSilicon ion enhanced cell proliferation and differentiation (fusion index by 1.5 times and overexpression of myogenic factors) in mouse myoblast precursor cells as compared to control. Qualitative live/dead analysis showed more abundance of live myoblast precursor cells (green) and decreased number of dead cells (red) on MAG‐Lp surface as compared to MAG (Fig. 1). We also show successful printing abilities of MAG‐Lp scaffolds in the volumetric muscle loss defect (Fig. 2) along with increased attachment to the adjacent tissues. The animal also showed ability to stand on/flex the surgical limb, with sufficient grip strength to perform normal activity, immediately after recovering from the surgery.ConclusionOur preliminary findings conclude that 3D printing of MAG‐Lp can enhance myogenesis in myoblasts. We further conclude that successful proof of concept of an in‐situ bioprinting method of reconstructive scaffolds can be used for immediate repair and loading of muscles for VML injury treatment.Support or Funding InformationNIH/NIDCR (R03DE023872‐01, 1R56DE027964‐01A1‐01), Texas STARs award, Departmental Start‐up Funds, University of Texas at Arlington, College of Nursing and Health Innovation, Arlington, TXshowing live/dead assay on MAG and MAG‐Lp scaffolds. Green represents live cells, whereas red represents dead cells.Figure 1showing In‐situ 3D printing biopolymer scaffold in a rat volumetric muscle loss model in tibialis anterior muscle (20–25% muscle loss) along with UV/photo curingFigure 2