Electrospun ultrathin PBAT/nHAp fibers influenced the in vitro and in vivo osteogenesis and improved the mechanical properties of neoformed bone

Abstract

Combining polyester scaffolds with synthetic nanohydroxyapatite (nHAp), which is bioactive and osteoconductive, is a plausible strategy to improve bone regeneration. Here, we propose the combination of PBAT [poly(butylene-adipate-co-terephthalate)] and synthetic nHAp (at 3 and 5wt%). PBAT is a relatively a new polymer with low crystallinity and attractive biodegradability and mechanical properties for orthopedic applications, however, with a still underexplored potential for in vivo applications. Then, we performed a careful biological in vitro and in vivo set of experiments to evaluate the influence of PBAT containing two different nHAp loads. For in vitro assays, osteoblast-like MG63 cells were used and the bioactivity and gene expression related to osteogenesis were evaluated by qRT-PCR. For in vivo experiments, twenty-four male rats were used and a tibial defect model was applied to insert the scaffolds. Micro-computed tomography (Micro-CT) and histological analysis were used to assess e bone neoformation after 6 weeks of implantation. Three point flexural tests measured the mechanical properties of the neoformed bone. All scaffolds showed promising in vitro properties, since they were not cytotoxic against MG-63 cells and promoted high cell proliferation and formation of mineralized nodules. From a mechanistic point-of-view, nHAp loading increased hydrophilicity, which in turn allowed for a better adsorption of proteins and consequent changes in the phenotypic expression of osteoblasts. nHAp induced better cellular responses on/in the scaffolds, which was mainly attributed to its osteoconductive and osteoinductive properties. Micro-CT images showed that nHAp at 3% and 5wt% led to more effective bone formation, presenting the highest bone volume after 6 weeks of implantation. Considering the three point flexural tests, 5wt% of nHAp positively influenced the flexural mode of the neoformed bone, but the stiffiness was similar between the 3% and 5wt% groups. In summary, this investigation demonstrated great potential for the application of these novel scaffolds towards bone regeneration and, thus, should be further studied.

Enhanced osteogenic activity with boron-doped nanohydroxyapatite-loaded poly(butylene adipate-co-terephthalate) fibrous 3D matrix

“…Moreover, recent studies have shown that it is biocompatible with many cell types. This property makes PBAT a promising synthetic polymeric biomaterial for tissue engineering applications [1][2][3][4][5][6]. Although synthetic biodegradable polymers have many advantages in terms of mechanical properties such as controlled biodegradation rate and processability into various functional shapes, they are lack of biological signals that limit their cell promotion [7].…”

Effect of nano-hydroxyapatite on protein adsorption and cell adhesion of poly(lactic acid)/nano-hydroxyapatite composite microspheres

“…It exists as Nano crystals in the organic/inorganic composite structure of human bones. The incorporation of HAP can endow the bioactivity and osteogenic activity, and improve cell affinity [6][7][8]. Therefore, the organic/inorganic composites by mimicking natural bone attract attentions, aiming to improve the natural process of bone regeneration.…”

An overview on properties and applications of poly(butylene adipate‐co‐terephthalate)–PBAT based composites

“…This synthetic BP is prepared by transterification reaction under controlled conditions, and therefore generally exhibit predictable and reproducible properties [14]. It can be used in several applications, such as packaging materials (trash bags, food containers, film wrapping), hygiene products (diaper back sheets, cotton swabs), biomedical fields, industrial composting, to name a few [25][26][27][28][29]. Biodegradation of PBAT depends on their chemical structure and environmental degrading conditions [30].…”