Novel high‐strength polyester composite scaffolds for bone regeneration

Abstract

Repair of critical‐sized bone defects, particularly in load‐bearing areas, is a major clinical problem that requires surgical intervention and implantation of biological or engineered grafts. For load‐bearing sites, it is essential to use engineered grafts that have both sufficient mechanical strength and appropriate pore properties to support bone repair and tissue regeneration. Unfortunately, the mechanical properties of such grafts are often compromised due to the creation of pores required to facilitate tissue ingrowth following implantation. To overcome the limitations associated with porous scaffolds and their reduced mechanical strength, we have developed a methodology for creating a solid structure that retains its bulk mechanical properties while also evolving into a porous structure in a biological environment through degradation and erosion. In this study, we utilized polyesters that have been approved by the FDA, including poly (lactic acid) (PLA), poly (glycolic acid) (PGA), their copolymer PLGA (PLGA, with a ratio of 85:15 and 50:50 of PLA:PGA), and poly (caprolactone) (PCL). These polymers and their ceramic composites with tricalcium phosphate (TCP) were compression molded into solid forms, which exhibited mechanical properties with compressive modulus as high as 2745 ± 364 MPa within the range of human trabecular bone and in the lower range of human cortical bone. The use of fast‐degrading PLGA (50:50) and PGA as porogens allowed the formation of pores within the solid structures due to their degradation, and the TCP acts as a buffering agent to neutralize their acidic degradation byproducts. These scaffolds facilitated the growth of new blood vessels and tissue ingrowth in a subcutaneous implantation model. In addition, in a rat critical‐sized mandibular bone defects these scaffolds supported bone growth with 70% of new bone volume fraction. Furthermore, the extent of bone regeneration was found to be higher for the scaffolds with bone morphogenic proteins (BMP2), indicating their suitability for bone repair and regeneration.

Computational Modelling and Simulation of Scaffolds for Bone Tissue Engineering

“…They must be: (i) nontoxic to host tissues (i.e., biocompatible), (ii) able to degrade their structure to give space for the growing bone cells (i.e., biodegradable) [34], (iii) able to permit the cells to stick and multiply on their surfaces to generate extracellular matrix (i.e., osteoconductive) [35], (iv) able to induce neo-bone tissues through mechanical stimulus (i.e., osteoinductive) [36], (v) able to form bone materials with the help of bone-forming cells 'osteoblasts' (i.e., osteogenic), (vi) able to integrate existing osseous tissues with their load-bearing surfaces (osteointegration) [37], (vii) exhibit appropriate morphological characteristics like pore size, porosity, and pore connectivity [38], and (viii) mirror the mechanical properties of the host tissues, including Young's modulus and compressive strength. These properties of scaffolds are influenced by their materials, such as synthetic and natural polymers, bio-composites, metal alloys and ceramics (Figures 3 and 4) [39][40][41].…”

A robust and biodegradable hydroxyapatite/poly(lactide-co-ε-caprolactone) electrospun membrane for dura repair

“…20–22 The FDA has also approved PLA and PCL as implantable degradable polymer materials. 23 The PLA electrospun membrane is deformation-resistant and has acceptable stiffness; however, it lacks hydrophilicity and toughness. 24 Despite having good toughness, the PCL electrospun membrane has a low elastic modulus and yield strength.…”