The influence of pregelatinized starch on the rheology of a gellan gum-collagen IPN hydrogel for 3D bioprinting

Abstract

Hydrogel scaffolds infused with stem cells are valuable alternatives to skin grafts in replacement of lost host tissues. In a prior study, we developed an adipose-derived stem cells (ADSC)-laden gellan gum-collagen interpenetrating network (IPN) hydrogel with enhanced wound healing properties upon application on murine full thickness burn wounds. With the perspective of enabling the clinical translation and healthcare adaptation of the hydrogel wound-dressing, we report a novel ADCS-laden collagen-gellan gum full IPN hydrogel formula compatible with 3D bioprinting technology. The stable new bio-ink showed improved printability for extrusion-based 3D biofabrication and preserved scaffold quality for stem cell proliferation. Pregelatinized starch (PGF, PREGEFLO®PI10) and glycerol were successfully incorporated to the bio-ink as molecular lubricant and hydrophilic plasticizer. When subjected to rheological measurements, the new glycerol-PGF-gellan gum composite hydrogel demonstrated good shear recovery ability, improved resistance to step-strain deformations and adequate stiffness as cell-conducive environment. Subsequently, a dual-head two-step temperature-guided 3D bioprinting methodology was developed to extrude ADSC-laden collagen into the composite hydrogel thick film to achieve in-situ polymer interpenetration. After their fabrication, the printed cell-laden hydrogel constructs were able to maintain high shape fidelity and stability after 21 days of incubation in cell culture media. Results from cell proliferation assay (MTS) and confocal laser scanning microscopy (CLSM) suggested that ADSC retained their normal cellular functions of adhesion, proliferation, and migration within the 3D bioprinted hydrogel scaffold. Taken together, our study brings forward the use of PREGEFLO®PI10 in upgrading the ADSC-laden IPN hydrogel formula towards potential clinical translation of synthetic skin grafts.