Comparison of bone morphogenetic protein‐2 and osteoactivin for mesenchymal cell differentiation: Effects of bolus and continuous administration

Abstract

Current osteoinductive protein therapy utilizes bolus administration of large doses of bone morphogenetic proteins (BMPs), which is costly, and may not replicate normal bone healing. The limited in vivo biologic activity of BMPs requires the investigation of growth factors that may enhance this activity. In this study, we utilized the C3H10T1/2 murine mesenchymal stem cell line to test the hypotheses that osteoactivin (OA) has comparable osteoinductive effects to bone morphogenetic protein-2 (BMP-2), and that sustained administration of either growth factor would result in increased osteoblastic differentiation as compared to bolus administration. Sustained release biodegradable hydrogels were designed, and C3H10T1/2 cells were grown on hydrogels loaded with BMP-2 or OA. Controls were grown on unloaded hydrogels, and positive controls were exposed to bolus growth factor administration. Cells were harvested at several time points to assess osteoblastic differentiation. Alkaline phosphatase (ALP) staining and activity, and gene expression of ALP and osteocalcin were assessed. Treatment with OA or BMP-2 resulted in comparable effects on osteoblastic marker expression. However, cells grown on hydrogels demonstrated osteoblastic differentiation that was not as robust as cells treated with bolus administration. This study shows that OA has comparable effects to BMP-2 on osteoblastic differentiation using both bolus administration and continuous release, and that bolus administration of OA has a more profound effect than administration using hydrogels for sustained release. This study will lead to a better understanding of appropriate delivery methods of osteogenic growth factors like OA for repair of fractures and segmental bone defects.

Low-Frequency Mechanical Stimulation Modulates Osteogenic Differentiation of C2C12 Cells

“…The present results confirm these findings and moreover demonstrate that lowfrequency mechanical stimulation can enhance osteogenic differentiation of C2C12 cells in the presence of BMP-2. BMP-2 alone induces expression of bone marker genes such as alkaline phosphatase (Alp), Osteopontin, and collagen type I [25], and we have clearly shown here that concomitant low-frequency mechanical stimulation has a synergistic effect on C2C12 osteogenic differentiation depending on the timing of these costimuli. These findings are consistent with those of previous studies involving significantly different mechanical conditions, notably higher oscillatory stimulation frequencies [26][27][28].…”

Nanofibrous yet injectable polycaprolactone-collagen bone tissue scaffold with osteoprogenitor cells and controlled release of bone morphogenetic protein-2

“…Since the necessity for high dosage amounts of BMP2 to achieve bone healing [15][16][17] is one of the major challenges faced in clinical research, this observation is particularly significant. The scaffold though has superior mechanical properties as compared to other injectable gel-based biomaterials, might not be enough to match the mechanical properties of in vivo bone.…”

“…To ensure that there is enough BMP2 remaining at the treatment site to have any therapeutic effect, BMP2 dosage of more than 100-fold of physiological concentration has to be introduced in the bone scaffolds. However, higher than natural BMP2 dosage (around 5 μg) leads to undesirable cytotoxic and inflammatory effects, increased osteoclastic activity (bone resorption), uncontrolled ectopic bone formation, and carcinoma [15][16][17]. Based on in vitro and in vivo studies, a low dose of BMP2 with a sustained release profile has been found optimal for osteogenesis [18][19][20].…”

Secreted Protein Acidic and Rich in Cysteines-like 1 Suppresses Aggressiveness and Predicts Better Survival in Colorectal Cancers

“…On other hands, previous studies showed that GPNMB, NDRG1, and IGF1R were cell differentiation markers (29)(30)(31). GPNMB (Glycoprotein NMB, Osteoactivin) was reported to be an essential protein during the differentiation of osteoblast (32). N-Myc downstream-regulated gene 1 (NDRG1), also named differentiation-related gene-1, is involved in the development of central nervous system (33).…”