Abstract
Poly(l-lactide-co-glycolide) (PLGA) porous scaffolds were modified with collagen type I (PLGA/coll) or hydroxyapatite (PLGA/HAp) and implanted in rabbits osteochondral defects to check their biocompatibility and bone tissue regeneration potential. The scaffolds were fabricated using solvent casting/particulate leaching method. Their total porosity was 85% and the pore size was in the range of 250–320 µm. The physico-chemical properties of the scaffolds were evaluated using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), sessile drop, and compression tests. Three types of the scaffolds (unmodified PLGA, PLGA/coll, and PLGA/HAp) were implanted into the defects created in New Zealand rabbit femoral trochlears; empty defect acted as control. Samples were extracted after 1, 4, 12, and 26 weeks from the implantation, evaluated using micro-computed tomography (µCT), and stained by Masson–Goldner and hematoxylin-eosin. The results showed that the proposed method is suitable for fabrication of highly porous PLGA scaffolds. Effective deposition of both coll and HAp was confirmed on all surfaces of the pores through the entire scaffold volume. In the in vivo model, PLGA and PLGA/HAp scaffolds enhanced tissue ingrowth as shown by histological and morphometric analyses. Bone formation was the highest for PLGA/HAp scaffolds as evidenced by µCT. Neo-tissue formation in the defect site was well correlated with degradation kinetics of the scaffold material. Interestingly, around PLGA/coll extensive inflammation and inhibited tissue healing were detected, presumably due to immunological response of the host towards collagen of bovine origin. To summarize, PLGA scaffolds modified with HAp are the most promising materials for bone tissue regeneration.
Highlights
Bone tissue has regenerative capacity, but when a critical size defect occurs, regeneration becomes very difficult or even impossible
In our more recent study, we showed that PLGA modification with hydroxyapatite (HAp) deposited by biomimetic approach is beneficial for osteoblast adhesion, infiltration, and proliferation in the entire volume of porous scaffold [21]
Fourier transform infrared (FTIR) spectra (Figure 2b) confirmed the presence of HAp coating on PLGA scaffold
Summary
Bone tissue has regenerative capacity, but when a critical size defect occurs, regeneration becomes very difficult or even impossible. Highly porous scaffolds based on resorbable polymers, such as poly(llactide-co-glycolide) (PLGA), are widely considered as bone tissue engineering (BTE) substrates. The porosity and interconnectivity of pores are important factors influencing cell infiltration, migration, vascularization, nutrient and oxygen flow, or removal of waste [8,9]. Several techniques such as porogen leaching, fiber bonding, electrospinning, 3D printing, or phase separation/freeze-drying have been developed to obtain scaffolds for BTE [10]
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