Biofunctionalized hydrogels are widely used in tissue engineering for bone repair. This study examines the bone regenerative effect of the blood-derived growth factor preparation of Hypoxia Preconditioned Serum (HPS) and its fibrin-hydrogel formulation (HPS-F) on drilled defects in embryonic day 19 chick femurs. Measurements of bone-related growth factors in HPS reveal significant elevations of Osteopontin, Osteoprotegerin, and soluble-RANKL compared with normal serum (NS) but no detection of BMP-2/7 or Osteocalcin. Growth factor releases from HPS-F are measurable for at least 7 days. Culturing drilled femurs organotypically on a liquid/gas interface with HPS media supplementation for 10 days demonstrates a 34.6% increase in bone volume and a 52.02% increase in bone mineral density (BMD) within the defect area, which are significantly higher than NS and a basal-media-control, as determined by microcomputed tomography. HPS-F-injected femur defects implanted on a chorioallantoic membrane (CAM) for 7 days exhibit an increase in bone mass of 123.5% and an increase in BMD of 215.2%, which are significantly higher than normal-serum-fibrin (NS-F) and no treatment. Histology reveals calcification, proteoglycan, and collagen fiber deposition in the defect area of HPS-F-treated femurs. Therefore, HPS-F may offer a promising and accessible therapeutic approach to accelerating bone regeneration by a single injection into the bone defect site.

Fracture healing failure affects millions globally, yet early molecular mechanisms remain poorly understood. This study aimed to characterize initial fracture response through analyzing peripheral blood hematology, multiplex cytokine profiles, and microRNA (miRNA) expression in fracture hematoma within the first 5 days post-injury. In a prospective cohort of 64 patients with acute clavicle fractures, we assessed hematological parameters, cytokine levels via multiplex immunoassays, and miRNA expression through RNA sequencing, and quantitative PCR (qPCR) validation. Fracture severity and time elapsed post-injury were key drivers of molecular response variability. Severe fractures (type C) were associated with older patient age and impaired hematological parameters, including reduced hemoglobin, erythrocyte counts, and hematocrit. Leukocyte counts declined over time, reflecting evolving systemic inflammation. Severity-dependent cytokines included eotaxin, interferon alpha-2 (IFNα2), interleukin-1 alpha (IL-1α), macrophage inflammatory protein-1 (MIP-1α), whereas interferon gamma-induced protein 10 (IP-10) and MIP-1α distinguished temporal healing phases. MiRNA profiling revealed 55 miRNAs with significant time-dependent expression changes (27 downregulated, 28 upregulated). Five key miRNAs (miR-140-5p, miR-181a-5p, miR-214-3p, miR-23a-3p, miR-98-5p) showed robust temporal patterns and enrichment in cytokine signaling pathways critical for bone repair. This work presents the first detailed molecular portrait of early human fracture healing, highlighting hematological, immune cytokine, and miRNA networks orchestrating repair. These insights provide a foundation for biomarkers development to predict healing outcomes and support precision-targeted interventions in fracture management.