Osteogenic differentiation of marrow stromal stem cells in porous hydroxyapatite ceramics

Abstract

Bioactive materials such as hydroxyapatite ceramics (HA) are known to show a stable interfacial bond with tissues (the bone bonding property has been especially well documented). However, the biological phenomenon on the material surface that evoke bone bonding is not well documented. To address this issue, composites of porous HA and rat marrow cells were implanted into ectopic (subcutaneous) sites. At 3 weeks after implantation, active osteoblasts lining the HA surface initiated bone formation, primarily as mature bone (lamellar type). Gene expression study using Northern blot analysis of the composites showed that alkaline phosphatase (ALP) and bone Gla protein (BGP) mRNAs began to appear at 2 weeks and the level of BGP mRNA at 4 weeks was comparable to that of cancerous bone. However, HA implantation without marrow cells did not show bone formation and neither BGP nor ALP mRNA were detected. These results indicate that the HA surface is able to support cell differentiation (osteoblastic phenotype expression of marrow stromal stem cells), as well as cell coordination resulting in mature bone formation that bonds to the HA.

Osteogenic Differentiation of Mesenchymal Stem Cells by Mimicking the Cellular Niche of the Endochondral Template

“…Various in vitro bone regeneration strategies have relied on the use of the osteogenic supplements (dexamethasone, ascorbic acid, and b-glycerophosphate) to induce mineralization in vitro, 12,13,49,51,[53][54][55][56][57][58][59][60][61][62] and each supplement has been shown to be imperative to induce mineralization of MSCs in vitro. 9,[11][12][13][14][15][16][17]22,29,[63][64][65][66][67] The main rationale behind the use of these supplements is to provide signaling proteins or enzymes to activate mineral production by MSCs.…”

A Novel Polymer-Synthesized Ceramic Composite Based System for Bone Repair: Osteoblast Growth on Scaffolds with Varied Calcium Phosphate Content

“…Further, calcium phosphates have shown excellent biocompatibility, a high degree of bone ingrowth, and enhanced bone formation when used as bone defect fillers [4][5][6]. Many currently available implant materials use a highly crystalline, poorly resorbable hydroxyapatite that liberates ions very slowly over long periods of time.…”

“…This drop may be due to the release of calcium ions and subsequent reprecipitation of hydroxyapatite onto the matrix surface. The reprecipitation of hydroxyapatite [Ca[o(PO 4 ) 6 OH 2 ] would occupy hydroxyl ions, leading to a decrease in pH. This decrease in pH may create a slightly cytotoxic environment for the cells, leading to lower cell numbers at early time points, with a gradual recovery due to proliferation of existing cells, as is seen in the later time points.…”

“…Other studies have shown limited colony occupancy of osteoblasts cultured on nanophase ceramics including hydroxyapatite [9]. According to x-ray diffraction patterns of the calcium phosphate formed within the composite matrices, there is good evidence that the calcium phosphate formed is nanophase hydroxyapatite [6]. Therefore if a certain percentage of the microsphere surface was nanophase hydroxyapatite, the osteoblasts may have been restricted in migration, and thus have been limited in proliferation.…”

The Effect of Simulated Microgravity by Three-Dimensional Clinostat on Bone Tissue Engineering

“…tion has been observed in the pore areas of the HA ceramics (9)(10)(11)(12)24,25). Importantly, the composites also exhibited healing effects when implanted into sites with Evidence suggests that mechanical stress, including gravity, is associated with osteoblast differentiation and bony defects (8).…”