JOT - 2026-07-01 - Journal Article
Biomimetic Hematoma Promotes Superior Bone Regeneration With Ultra-low-Dose rhBMP-2 in a Goat Large-Defect Model.
Glatt V, Aguilar L, Agarwal A, Woloszyk A
Topics
Key Takeaway
A biomimetic hematoma scaffold delivering 42 µg rhBMP-2 achieved superior predicted torsional strength (highest pMOI, p<0.0001) in a 2.5 cm goat tibial defect compared to ACS delivering 50-fold higher dose (2.1 mg rhBMP-2).
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Summary
This study compared ultra-low dose rhBMP-2 (42 µg and 210 µg) delivered via autologous biomimetic hematoma scaffold versus standard ACS with 2.1 mg rhBMP-2 in a 2.5 cm goat tibial critical-size defect model. Radiographic scores at 8 weeks showed complete regeneration in both BH groups (5.0 and 4.7) versus 4.3 for ACS and 2.6 for empty defect (p<0.001). The BH+42 µg group demonstrated the highest predicted torsional strength by pMOI despite the lowest rhBMP-2 dose, while the BH+210 µg group produced the most histologically mature bone architecture.
Key Limitation
n=3 per group makes all statistical comparisons unreliable and prevents any generalization of findings.
Original Abstract
OBJECTIVE
The aim of this study was to evaluate whether an ultra-low dose of recombinant human bone morphogenetic protein-2 (rhBMP-2) delivered within a biomimetic hematoma (BH) scaffold could regenerate a large bone defect in goats more efficiently than a high dose of rhBMP-2 delivered on an absorbable collagen sponge (ACS). The BH is an autologous scaffold, created from whole blood and defined concentrations of coagulants, and is designed to closely mimic the structural and biological properties of a naturally healing fracture hematoma. It initiates the body's intrinsic healing cascade, thereby recapitulating the sequential phases of bone repair.
METHODS
A 2.5-cm defect was created in goat tibias and treated with either a BH scaffold containing ultra-low doses of rhBMP-2 (210 and 42 μg) or ACS with 2.1 mg of rhBMP-2. Empty defects and contralateral tibias served as controls. Bone regeneration was evaluated biweekly using radiographs and further assessed with micro-CT and histology at 8 weeks.
RESULTS
A total of 12 specimens, three per group, were used for radiographic, micro-CT, and histological evaluations. By 8 weeks, radiographic scores showed complete regeneration in the BH+210 µg (5.0 ± 0.0) and BH+42 µg (4.7 ± 0.2) groups. The ACS+2.1 mg group scored 4.3 ± 0.4 with some unmineralized regions while the ED group showed limited healing (2.6 ± 0.2; P < 0.001 vs. all other groups). Micro-CT analysis demonstrated significant differences in TV and BV between the BH group treated with 210 μg of rhBMP-2 and that treated with 42 μg of rhBMP-2 (TV: P = 0.02; BV: P = 0.009), and between the ACS+2.1 mg rhBMP-2 group and the BH+42 μg rhBMP-2 group (BV: P = 0.05), with the higher dose BH group showing significantly lower values than the other rhBMP-2 groups. Notably, the BH+42 µg group showed superior bone structural quality, with the highest predicted torsional strength ( P < 0.0001 vs. all groups). Histological observations revealed that BH+210 µg rhBMP-2 generated the most mature and organized bone architecture, closely resembling native tissue. By contrast, BH+42 µg showed ongoing remodeling with residual cartilage, while in the ACS+2.1 mg group, the marrow space remained filled with dense bone. The ED group predominantly contained fibrocartilage and collapsed muscle within the defect.
DISCUSSION
This study demonstrated that the BH scaffold, an autologous biodegradable matrix, enabled delivery of ultra-low rhBMP-2 doses that achieved rapid and consistent bone regeneration and outperformed the clinically used ACS. This has significant clinical implications, as the BH scaffold offers a promising biomaterial-free solution for precise rhBMP-2 delivery, enhancing rapid bone regeneration while minimizing dosage, reducing adverse effects, and lowering treatment costs, making it an effective intervention for complex bone injuries.