Lipid Mictrotubes as a Nutrient Reservoir or Enzyme Delivery Vehicle in Engineered Cartilage

Tissue-engineered cartilage using a hydrogel scaffold is capable of achieving native compressive properties and glycosaminglycan (GAG) content [1]. However, these tissues are limited in their collagen production and closer inspection of the localized mechanical properties demonstrates that mature constructs consist of a stiffer periphery region surrounding a softer core [1, 2]. Nutrient diffusion becomes increasingly more challenging as the cells in the construct periphery deposit extracellular matrix. Altering the scaffold porosity by adding microscopic porogens can improve the nutrient diffusion into the center of the construct [3]. Furthermore, chondroitinase ABC (chABC) has been shown to improve collagen production of mature engineered cartilage (i.e. tissue cultured for 2–4 weeks before chABC digestion). Lipid microtubes, designed to slowly release chABC for spinal chord injury repair can be incorporated into our agarose hydrogel scaffold in a chABC-loaded or unloaded form. The objective of this study was to explore the use of lipid microtubes in our scaffold as a tubular porogen and as a vehicle to deliver chABC throughout the scaffold to improve nutrient diffusion and collagen production into our engineered constructs.