Objective     To study the possibility of bone marrow stromal stem cells (BMSCs)-derived allogeneic osteoblasts (OBs)/vascular endothelial cells (VECs) combined with allogeneic morselized bone grafts for treating rat traumatic osteonecrosis of the femoral head (ONFH).     Methods      Thirty-six six-month-old SD rats were divided into three groups: model group

allogeneic bone group

and OB+VEC+allogeneic bone group

each including 12 rats. BMSCs

extracted from 4-week-old SD rats

were cultured in vitro

and the obtained third-generation cells were combined with allogeneic morselized bone. An animal model for rat traumatic ONFH was built through removing round ligaments of femoral heads

and the animals were sacrificed in the first

second

fourth

and sixth weeks after implanting OB+VEC+allogeneic morselized bone or allogeneic morselized bone to collect the femoral heads. The growth of OBs and VECs on allogeneic morselized bone was observed with a scanning electronic microscope. The expression of CD34 and CD31 in VECs was detected through an immunocytochemical method. OBs were identified through alkaline phosphatase (ALP) staining and collagen type-Ⅰ immunocytochemical staining. OBs and VECs were labeled with 5-bromo-2-deoxy uridine (BrdU) in vitro

so as to trace the kinetics of OBs and VECs in vivo. Pathological morphology changes were observed with an optical microscope. New bone formation was calculated according to bone histomorphometry parameters

including percent trabecular area (%Tb.Ar)

trabecular bone thickness (Tb.Th)

trabecular bone number (Tb.N)

and trabecular bone separation degree (Tb.Sp).     Results    ALP staining and collagen type-Ⅰ immunohistochemical staining of the BMSC-derived OBs gave positive results. The VECs expressed CD31 and CD34. The OBs and VECs exhibited excellent biocompatibility with the allogeneic bone

and were in good spreading

extension

and growth conditions on its surfaces. The OB+VEC+allogeneic bone group accomplished more new bone formation than the model group and allogeneic bone group

and each new bone formation parameter of the OB+VEC+allogeneic bone group was higher than those in the model group and allogeneic bone group (P0.01).     Conclusion     The OB+VEC+allogeneic bone composite has higher ability to promote new bone formation in treatment of rat traumatic ONFH than allogeneic morselized bone alone.