Recombinant human bone morphogenetic protein (BMP) 2A was purified and characterized, showing its ability to induce bone formation in rats. The study demonstrated that implantation of recombinant BMP-2A resulted in cartilage formation by day 7 and bone formation by day 14. The time of bone formation depended on the dose, with higher doses leading to bone formation as early as 5 days. The activity of recombinant BMP-2A was histologically indistinguishable from that of bone extracts, indicating its potential for promoting de novo bone formation in humans. The study involved the purification of BMP-2A from Chinese hamster ovary (CHO) cells using various chromatographic techniques. The protein was analyzed using immunological methods, including the production of antibodies against different fragments of BMP-2A. The results showed that BMP-2A exists in multiple forms, including 30-kDa, 80-kDa, and 110-kDa species, with the 30-kDa form being the most abundant and active. The study also examined the effects of different doses of BMP-2A on cartilage and bone formation. Higher doses led to more consistent cartilage and bone formation, with the 30-kDa form showing similar activity to the 80-kDa form. The 110-kDa form showed significantly less activity. The results indicated that BMP-2A can induce cartilage and bone formation in the rat ectopic model, suggesting its potential for therapeutic use in bone regeneration. The study concluded that recombinant BMP-2A has therapeutic potential for promoting bone formation in humans. The findings suggest that BMP-2A can initiate the classic pattern of endochondral ossification, similar to that seen with demineralized bone matrix or purified BMPs. The study also highlighted the importance of delivery methods and the role of the matrix in enhancing the sensitivity of the assay. The results indicate that BMP-2A can be used in applications requiring bone replacement and bone formation.Recombinant human bone morphogenetic protein (BMP) 2A was purified and characterized, showing its ability to induce bone formation in rats. The study demonstrated that implantation of recombinant BMP-2A resulted in cartilage formation by day 7 and bone formation by day 14. The time of bone formation depended on the dose, with higher doses leading to bone formation as early as 5 days. The activity of recombinant BMP-2A was histologically indistinguishable from that of bone extracts, indicating its potential for promoting de novo bone formation in humans. The study involved the purification of BMP-2A from Chinese hamster ovary (CHO) cells using various chromatographic techniques. The protein was analyzed using immunological methods, including the production of antibodies against different fragments of BMP-2A. The results showed that BMP-2A exists in multiple forms, including 30-kDa, 80-kDa, and 110-kDa species, with the 30-kDa form being the most abundant and active. The study also examined the effects of different doses of BMP-2A on cartilage and bone formation. Higher doses led to more consistent cartilage and bone formation, with the 30-kDa form showing similar activity to the 80-kDa form. The 110-kDa form showed significantly less activity. The results indicated that BMP-2A can induce cartilage and bone formation in the rat ectopic model, suggesting its potential for therapeutic use in bone regeneration. The study concluded that recombinant BMP-2A has therapeutic potential for promoting bone formation in humans. The findings suggest that BMP-2A can initiate the classic pattern of endochondral ossification, similar to that seen with demineralized bone matrix or purified BMPs. The study also highlighted the importance of delivery methods and the role of the matrix in enhancing the sensitivity of the assay. The results indicate that BMP-2A can be used in applications requiring bone replacement and bone formation.