Deferoxamine improves femoral trochlear dysplasia following patellar dislocation through HIF-1α/VEGF-mediated angiogenesis-osteogenesis coupling

Patellar dislocation (PD) is closely associated with femoral trochlear dysplasia, yet the underlying molecular mechanisms remain unclear. This study aims to investigate the role of HIF-1α/VEGF-mediated angiogenesis-osteogenesis coupling in trochlear dysplasia following PD and to evaluate the therapeutic potential of the iron chelator deferoxamine (DFO) through HIF-1α stabilization.

The PD model was established in 4-week-old male C57BL/6 N mice, which were then randomly divided into three groups: Sham, PD, and DFO. The DFO group received intra-articular injections of DFO (100 mg/kg, 20 µl) every five days postoperatively. Distal femurs were collected 30 days after surgery. RT-qPCR and Western blot were used to detect the expression of HIF-1α, VEGF, and RUNX2, ALP, and OPN osteogenic markers. The trochlear morphology assessment including sulcus angle and trochlear depth, along with bone microarchitecture parameters such as BV/TV, BMD, Tb.N, Tb.Th, and Tb.Sp, were quantified using micro-CT. Cartilage degeneration was evaluated with HE, Alcian blue, and Safranin O/fast green staining. Immunohistochemistry (IHC) was used to detect the expression of COL2A1 in tissue sections. Statistical analyses were performed using SPSS 21.0, with significance set at P < 0.05.

Compared with the Sham group, the PD group showed significantly decreased mRNA and protein expression of HIF-1α and VEGF, accompanied by reduced expression of osteogenic-specific genes (RUNX2, ALP, OPN). DFO treatment reversed these changes. Micro-CT revealed significantly increased sulcus angle and decreased trochlear depth in the PD group, with partial restoration of trochlear morphology in the DFO group. Regarding bone microstructure, the PD group exhibited decreased BV/TV, BMD, Tb.N and Tb.Th, along with increased Tb.Sp, while DFO treatment improved these bone parameters. Histological and IHC analyses demonstrated reduced cartilage thickness, diminished chondrocyte populations, disrupted structural organization and decreased COL2A1 expression in the PD group, but DFO treatment alleviated cartilage degeneration.

HIF-1α/VEGF-mediated angiogenesis-osteogenesis coupling plays an important role in trochlear dysplasia following PD. Intra-articular injections of DFO improve trochlear morphology, bone microstructure, and reduce cartilage degeneration by stabilizing HIF-1α to upregulate VEGF and osteogenic markers (RUNX2, ALP, OPN).