Superior calvarial bone regeneration using pentenoate-functionalized hyaluronic acid hydrogels with devitalized tendon particles

Traumatic brain injury (TBI) is a life-threatening condition defined by internal brain herniation. Severe TBI is commonly treated by a two-stage surgical intervention, where decompressive craniectomy is first conducted to remove a large portion of calvarial bone and allow unimpeded brain swelling. In the second surgery, spaced weeks to months after the first, cranioplasty is performed to restore the cranial bone. Hydrogels with paste-like precursor solutions for surgical placement may potentially revolutionize TBI treatment by permitting a single-stage surgical intervention, capable of being implanted with the initial surgery, remaining pliable during brain swelling, and tuned to regenerate calvarial bone after brain swelling has subsided. The current study evaluated the use of photocrosslinkable pentenoate-functionalized hyaluronic acid (PHA) and non-crosslinking hyaluronic acid (HA) hydrogels encapsulating naturally derived tissue particles of demineralized bone matrix (DBM), devitalized cartilage (DVC), devitalized meniscus (DVM), or devitalized tendon (DVT) for bone regeneration in critical-size rat calvarial defects. All hydrogel precursors exhibited a yield stress for placement and addition of particles increased the average material compressive modulus. The HA-DBM (4-30%), PHA (4%), and PHA-DVT (4-30%) groups had 5 (p < 0.0001), 3.1, and 3.2 (p < 0.05) times greater regenerated bone volume compared to the sham (untreated defect) group, respectively. In vitro cell studies suggested that the PHA-DVT (4-10%) group would have the most desirable performance. Overall, hydrogels containing DVT particles outperformed other materials in terms of bone regeneration in vivo and calcium deposition in vitro. Hydrogels containing DVT will be further evaluated in future rat TBI studies. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.