Repairing calvarial defects with novel biodegradable polycaprolactone-chitosan three-dimensional scaffolds

Objectives: Polycaprolactone (PCL)-chitosan (CS) three-dimensional scaffolds have been successfully fabricated using the Melt Stretching and Multilayer Deposition (MSMD) technique. In vitro, the PCL-CS scaffolds containing 20% CS (PCL-20%CS) showed promising results of supporting growth and differentiation of the osteoblasts when compared to other ratios. In this study, the ability of repairing bone defects of the PCL-20%CS scaffolds was assessed in animal models. New bone regeneration within the rabbit’s calvarial defects conducted by the scaffolds was assessed and compared with commercial scaffolds for benchmarking.

Methods: Two critical-sized defects were created at each site of the calvarium in nine New Zealand white rabbits. The PCL- 20%CS scaffolds were randomly implanted in one site (group A) and another site were implanted with PCL-Tricacium phosphate (TCP) scaffolds containing 20% TCP (PCL-20%TCP; Osteopore^TM, Singapore) (group B). At two, four and eight weeks thereafter, new bone regeneration within the defects was assessed using micro-CT and histomorphometric measurements (n=3/group/time point).

Results: The percentages of new bone formation in group B were greater than those of group A at all time points (p < 0.05). From observing both groups, the bone formation mainly coming from the periphery of the host bone and the covering periosteum tended to bridge the defects.

Conclusions: In conclusion, bone regeneration could be conducted by the PCL-20%CS MSMD scaffolds. However, their maturity of the new bones might take longer time than that of the PCL-20%TCP scaffolds. Possible reasons were also discussed for improving the fabrication technique.