Regeneration enhanced in critical-sized bone defects using bone-specific extracellular matrix protein.

Extracellular matrix (ECM) products have the potential to improve cellular attachment and promote tissue-specific development by mimicking the native cellular niche. In this study, the therapeutic efficacy of an ECM substratum produced by bone marrow stem cells (BM-MSCs) to promote bone regeneration in vitro and in vivo were evaluated. Fluorescence-activated cell sorting analysis and phenotypic expression were employed to characterize the in vitro BM-MSC response to bone marrow specific ECM (BM-ECM). BM-ECM encouraged cell proliferation and stemness maintenance. The efficacy of BM-ECM as an adjuvant in promoting bone regeneration was evaluated in an orthotopic, segmental critical-sized bone defect in the rat femur over 8 weeks. The groups evaluated were either untreated (negative control); packed with calcium phosphate granules or granules+BM-ECM free protein and stabilized by collagenous membrane. Bone regeneration in vivo was analyzed using microcomputed tomography and histology. in vivo results demonstrated improvements in mineralization, osteogenesis, and tissue infiltration (114 ± 15% increase) in the BM-ECM complex group from 4 to 8 weeks compared to mineral granules only (45 ± 21% increase). Histological observations suggested direct apposition of early bone after 4 weeks and mineral consolidation after 8 weeks implantation for the group supplemented with BM-ECM. Significant osteoid formation and greater functional bone formation (polar moment of inertia was 71 ± 0.2 mm4 with BM-ECM supplementation compared to 48 ± 0.2 mm4 in untreated defects) validated in vivo indicated support of osteoconductivity and increased defect site cellularity. In conclusion, these results suggest that BM-ECM free protein is potentially a therapeutic supplement for stemness maintenance and sustaining osteogenesis.

Augmentation of mast cell bactericidal activity by the anti-leukemic drug, 4-(3'bromo-4'-hydroxylphenyl)-amino-6,7-dimethoxyquinazoline.

Mast cells play a pivotal role in host innate immune defense against gram negative bacterial infections by killing gram negative bacteria and recruiting neutrophils to the sites of active infection through the release of TNFalpha and leukotrienes. Here, we report that the anti-leukemic compound 4-(3'bromo-4'-hydroxylphenyl)-amino-6,7-dimethoxyquinazoline, designated as MASTPROM, augments the bactericidal activity of mast cells by increasing the binding of bacteria to and their phagocytosis by mast cells. MASTPROM also promoted the bacterial clearance in a mouse model of bacterial peritonitis. MASTPROM may provide the basis for novel supportive care regimens aimed at augmenting the bactericidal activity of mast cells and thereby potentiating the innate immune response against gram negative organisms.