Abstract
Tissue engineering is a promising strategy for bone tissue defect reconstruction. Immunogenic reaction, which was induced by scaffolds degradation or contaminating microorganism, influence cellular activity, compromise the efficiency of tissue engineering, or eventually lead to the failure of regeneration. Inhibiting excessive immune response through modulating scaffold is critical important to promote tissue regeneration. Our previous study showed that ε-poly-L-lysine (EPL)-coated nanoscale polycaprolactone/hydroxyapatite (EPL/PCL/HA) composite scaffold has enhanced antibacterial and osteogenic properties in vitro. However, the bone defect repair function and immunogenic reaction of EPL/PCL/HA scaffolds in vivo remains unclear. In the present study, three nanoscale scaffolds (EPL/PCL/HA, PCL and PCL/HA) were transplanted into rabbit paraspinal muscle pouches, and T helper type 1 (Th1), T helper type 2 (Th2), T helper type 17 (Th17), and macrophage infiltration were analyzed after 1 week and 2 weeks to detect their immunogenic reaction. Then, the different scaffolds were transplanted into rabbit calvarial bone defect to compare the bone defect repair capacities. The results showed that EPL/PCL/HA composite scaffolds decreased pro-inflammatory Th1, Th17, and type I macrophage infiltration from 1 to 2 weeks, and increased anti-inflammatory Th2 infiltration into the regenerated area at 2 weeks in vivo, when compared to PCL and PCL/HA. In addition, EPL/PCL/HA showed an enhanced bone repair capacity compared to PCL and PCL/HA when transplanted into rabbit calvarial bone defects at both 4 and 8 weeks. Hence, our results suggest that EPL could regulate the immunogenic reaction and promote bone defect repair function of PCL/HA, which is a promising agent for tissue engineering scaffold modulation.
Highlights
Tissue engineering is a promising strategy for bone tissue defect reconstruction
3D printed PCL/HA scaffold coated by 5-mg/ ml ε-poly-l-lysine (EPL) have been successfully build as a new EPL/PCL/HA composite scaffold
When implanted into the rabbit muscle, it showed that the EPL/PCL/HA promotes tissue regeneration in the muscle transplant model and decreased pro-inflammatory Th1, Th17, and type I macrophage infiltration, and increased anti-inflammatory Th2 infiltration into the regenerated area, when compared to PCL and PCL/HA
Summary
Bone tissue defects are frequently occurring craniomaxillofacial issues that arise from multiple sources including tumors, trauma, congenital malformations, and senile osteoporosis [1]. Tissue engineering is a promising strategy for bone tissue defect reconstruction. In order to improve the tissue repair efficacy, numerous researches have focus on the scaffold properties, degradation, and clearance [2, 3]. Despite the great achievement have been made, challenges and obstacles still exist, which limit the tissue repair efficacy and clinical application [4]. The cross talk between scaffold and tissue plays a central role in tissue engineering [5, 6]. Clarifying and regulating the biology interaction between scaffold and tissue are critically important to the improvement of the tissue repair efficacy.
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