Collagen/hyaluronic acid-based hydrogels for brain applications: the role of hyaluronic acid molecular weight

Hydrogels made from a number of natural and synthetic polymers have been studied for their ability to deliver therapeutics directly into the central nervous system1. In particular, hyaluronic acid (HA)-based gels have been used to deliver trophic factors2 or cells into the injured spinal cord3. Type I collagen (COLL) is also an appealing candidate for neural tissue regeneration. In fact it self-assembles to form a fibrillar structure at physiological conditions and interacts with cells to guide their adhesion, migration, survival, proliferation, and differentiation4. The aim of the present work has been designing and characterizing injectable COLL/HA acid-based semi-interpenetrating polymer networks (semi-IPNs) for the delivery of neuroprotective proteins (e.g. 70 kDa-heat shock proteins, Hsp70) or cells in the treatment of Alzheimer’s and Parkinson’s diseases, focusing on the role of HA molecular weight.