Flow cytometry for assessing biocompatibility

Abstract

Flow cytometry (FCM) was examined as a possible procedure for measuring in vitro the biocompatibility of implant materials for orthopedic and dental surgery. The human osteoblast-like cell line MG63 was grown on hydroxyapatite (HA) and P2O5 glass-reinforced HA composite discs and compared with the same cells grown on polystyrene culture dishes. While morphological observation at the light and electron microscopic levels showed no major deleterious effects, FCM indicated that cell size was somewhat reduced, particularly by growth on the HA composite. Morever, this material also appeared to delay the progression of the cells from the G0/G1 into the S phase of the cell cycle. In addition to this low level of inhibition of cell growth relative to control cultures, FCM analysis also demonstrated that the glass-reinforced HA caused some down-regulation of the expression of osteocalcin and fibronectin, two antigens which play a vital part in the integrity and function of bone and soft connective tissue, respectively. These results thus show, first, that although HA and the HA composite used in these experiments were generally biocompatible, they nevertheless had certain suboptimal effects on the cells; and second, that FCM could be a highly useful procedure for effectively screening and evaluating important biological responses to implant materials.

Histological and scanning electron microscopy analyses of bone/implant interface using the novel Bonelike® synthetic bone graft

“…13,28,29 Furthermore, Bonelike 1 enhanced the mineralization process compared to unmodified HA, which was a clear indication of its osteoconductive behavior.…”

Mechanical and cytotoxicity testing of acrylic bone cement embedded with microencapsulated 2‐octyl cyanoacrylate

“…MG63 human osteosarcoma cells have been used in numerous biocompatibility studies because they share several features with normal human osteoblasts, including secretion of insulin‐like growth factor, binding proteins, matrix metalloproteinases, and osteocalcin. Similar to undifferentiated osteoblasts, MG63 cells also synthesize collagen types I and III and have a low basal expression of alkaline phosphatase that is increased in response to 1,25‐dihydroxyvitamin D 3.…”

Hydroxyapatite and tricalcium phosphate composites with bioactive glass as second phase: State of the art and current applications

“…In spite of the complications associated to the presence of glass, the addition of a bioactive glassy phase may be advantageous, since the glass is expected to act as a sintering aid, promoting the densification and enhancing the mechanical properties of the composite with respect to the original HA. For this reason, the first attempts to produce glass/HA composites date back to the early ‘90s, mainly thanks to the works by Santos and Knowles …”

“…In the same way, while some authors observed surface degradation processes together with apatite formation in vitro on phosphate glass/HA composites, other authors did not detect such phenomena . For these reasons, many studies, which aim to predict the biocompatibility and the bone bonding ability of phosphate glass/HA samples, go beyond SBF assays and employ osteoblast‐like cell line cultures and/or animal models . Moreover, many works are focused on phosphate glass compositions other than the basic CaO‐P 2 O 5 one, obtained by adding specific ions such as Na, Mg, K, or F, aiming to reach the best compromise between the mechanical performance of the material and its biological responsiveness.…”