Biodegradable polymer/hydroxyapatite composites: Surface analysis and initial attachment of human osteoblasts

Abstract

Biodegradable polymer/hydroxyapatite (HA) composites have potential application as bone graft substitutes. Thin films of polymer/HA composites were produced, and the initial attachment of primary human osteoblasts (HOBs) was assessed to investigate the biocompatibility of the materials. Poly(epsilon-caprolactone) (PCL) and poly(L-lactic acid) (PLA) were used as matrix materials for two types of HA particles, 50-microm sintered and submicron nonsintered. Using ESEM, cell morphology on the surfaces of samples was investigated after 90 min, 4 h, and 24 h of cell culture. Cell activity and viability were assessed after 24 h of cell culture using Alamar blue and DNA assays. Surface morphology of the polymer/HA composites and HA exposure were investigated using ESEM and EDXA, respectively. ESEM enabled investigation of both cell and material surface morphology in the hydrated condition. Combined with EDXA it permitted chemical and visual examination of the composite. Differences in HA exposure were observed on the different composite surfaces that affected the morphology of attached cells. In the first 4 h of cell culture, the cells were spread to a higher degree on exposed HA regions of the composites and on PLA than they were on PCL. After 24 h the cells were spread equally on all the samples. The cell activity after 24 h was significantly higher on the polymer/HA composites than on the polymer films. There was no significant difference in the activity of the cells on the various composite materials. However, cells on PCL showed higher activity compared to those on PLA. A polymer surface exhibiting "point exposure" of HA appeared to provide a novel and favorable substrate for primary cell attachment. The cell morphology and activity results indicate a favorable cell/material interaction and suggest that PLA and PCL and their composites with HA may be candidate materials for the reconstruction of bony tissue. Further investigations regarding long-term biomaterial/cell interactions and the effects of acidic degradation products from the biodegradable polymers are required to confirm their utility.

Technologies Applied to Stimulate Bone Regeneration

“…Osteoblast cell cultures in porous PLLA/hydroxyapatite composites (PLLA-HA) enable cell proliferation, the lodging of cells throughout the scaffold of the biomaterial and the differentiation of these cells with synthesis of mineralized matrix (Ma et al, 2001). These results are corroborated by the study of Rizzi and collaborators with the biomaterial of PLA-HA and PCL-HA (Rizzi et al 2001). HA induces the activity of the bone cells preferentially adhered to these particles, exposed on the surface of the composite.…”

Calcium orthophosphate-based biocomposites and hybrid biomaterials

“…The combination of calcium orthophosphates and polymers into biocomposites has a twofold purpose. The desirable mechanical properties of polymers compensate for a poor mechanical behavior of calcium orthophosphate bioceramics, while in turn the desirable bioactive properties of calcium orthophosphates improve those of polymers, expanding the possible uses of each material within the body [127][128][129][228][229][230][231]. Namely, polymers have been added to calcium orthophosphates in order to improve their mechanical strength [127,228] and calcium orthophosphate fillers have been blended with polymers to improve their compressive strength and modulus, in addition to increase their osteoconductive properties [48,129,137,[232][233][234][235][236].…”

Osteoblast, fibroblast and in vivo biological response to poly(vinylidene fluoride) based composite materials

“…Cell culture techniques have been extensively used for the study of cell/biomaterial interactions allowing the investigation of the biomaterial cytotoxicity and biocompatibility. The cell attachment on the biomaterials is considered to be one of the most important stages in cell/ biomaterial interaction [18]. The in vivo interactions are more complex than those in vitro, which do not reflect the whole body response of the organism such as immune and inflammatory response [19].…”