Plant Derived Cellulose Scaffolds as a Novel Biomaterial for 3D Cell Culture and Tissue Regeneration

Abstract

This work presents an alternative approach to the production of cellulose-based biomaterials. Instead of extracting, processing and regenerating plant and or bacteria-derived cellulose into a biomaterial, my work established a decellularization protocol to remove cellular plant content from plant tissue resulting in a scaffold composed of cellulose with the evolved architecture of the plant cell wall. Tracheophyte plants, including clubmosses, horsetails, and ferns, gymnosperms and angiosperms, have evolved distinct vascular structures that support the transport of water and nutrients in xylem and phloem that form the vascular bundles (VBs)1. This thesis took it’s inspiration from the dense, linearly arranged, parallel microchannels which include (VBs) in the stalks of Asparagus officinalis possess an architecture with striking similarities to biomaterial scaffolds intended to repair damaged tissue. My work demonstrated that the plant cell wall contains many of the ideal characteristics of a medical biomaterial. The scaffold is biocompatible with mammalian cells and maintains high viability even with cell densities comparable to commercially available scaffolds. The cellulose scaffold could be biochemically functionalized or cross-linked to control the scaffolds' surface biochemistry and mechanical properties. My in vivo model demonstrated that the lignocellulose scaffold did not elicit a foreign body response. The scaffold was permissive to host cell invasion, including active host fibroblast, leading to the deposition of host collagen extracellular matrix. Importantly, active blood vessels formed within the scaffold to support the population of host cells. The scaffold retained much of its original shape and provided an inert, pro-vascular long-term environment for host cells to invade. Taken together, this led to the hypothesis that the innate plant cell wall architecture could restore the function of injured tissue, specifically that the vascular bundles could be used to promote axonal regeneration in spinal cord injuries. Rats with complete spinal cord transection were implanted with cellulose scaffolds with vascular bundles. Animals that received plant-derived scaffolds demonstrated a significant improvement in motor function. This thesis defines a novel and parallel route for exploiting naturally occurring plant microarchitectures of the underlying crystalline cellulose scaffold.