Bone regeneration using an acellular extracellular matrix and bone marrow mesenchymal stem cells expressing Cbfa1.

To treat bone defects, tissue-engineering methods combine an appropriate scaffold with cells and osteogenic signals to stimulate bone repair. Mesenchymal stem cells (MSCs) derived from adult bone marrow are an ideal source of cells for tissue engineering, in particular for applications in skeletal and hard tissue repair. Core binding factor alpha1 (Cbfa1) is an essential transcription factor for osteoblast differentiation. However, the effects of Cbfa1 on MSCs in vitro and in vivo have not been well characterized. In this study, we found that MSCs modified genetically to express Cbfa1 promoted the healing of segmental defects of the radius in rabbits. First, osteogenic differentiation of MSCs transfected with an adenovirus encoding Cbfa1 was demonstrated. Expression of mRNA from a number of osteoblastic marker genes, including osteocalcin, osteopontin, and type I collagen, was detected. In addition, alkaline phosphatase activity and increased osteocalcin content were observed. The cells expressing the Cbfa1 gene were then combined with acellular bone extracellular matrix in a flow perfusion culture system. Finally, the cell-matrix constructs were implanted into radius defects in the rabbit model. After 12 weeks, radiographic, histological, and biomechanical analyses showed that MSCs modified with the Cbfa1 gene resulted in a significantly higher amount of newly-formed bone and rebuilding of the marrow cavity than control cell-matrix constructs. This study indicates that MSCs modified with the Cbfa1 gene can act as suitable seed cells for the regeneration of bone defects.

Stereoscopic study on capillary density of early brain oedema in a dog postburn model.

BACKGROUND: After severe burn, the effective circulating blood volume decreases drastically due to massive body fluid loss, and blood redistribution occurs to maintain sufficient blood supply to vital organs. Blood perfusion of brain tissue changes and the permeability of the blood brain barrier increases due to ischaemia and hypoxia, which results in brain oedema. The goal of this study was to explore the changes of cerebral blood flow during the brain oedema at the early stage of severe burn. METHODS: Twenty-six dogs were randomly divided into control and 6, 12, 18, and 24 PBH groups. The manifestation of MRI and histopathology, changes of brain water content were investigated; the shapes and distribution of the cerebral capillaries were observed with the endogenous AKP histochemical staining method and image analysis technique. The volume, surface, and length fractions of cerebral capillaries were tested and analysed with a stereographic method in each group, respectively. RESULTS: The earliest changes of cerebral oedema were found at 12 PBH with MRI, which showed the brain swelling as characteristic of cerebral morphological changes. The decrease of SIR on T(1)WI was not observed until it was above 10%. Signal of T(2)WI increased for 8.29% at 24 PBH. Histological changes were observed as early as 6h after burn, accompanied by swelling of endothelial cells and peri-vascular astrocytes, vacuolation took place in neurons at 12h after burn, necrosis of different degrees in capillary endothelium, neurons, and axons. Increase in cerebral water content was noted at 6h postburn, and it was the most marked in 24 postburn group.The distributional density of capillaries became thicker at 6h and 12h postburn, the shapes were normal. The capillaries became sparser at 18h, and almost disappeared from view, only a few ends of capillaries in the shape of vine were seen at 24h postburn. The percentages of capillary volume, surface, and length fractions were increased at 6h and 12h, but decreased at 18h and reached the lowest point at 24h postburn (P<0.05). CONCLUSION: We suggest that the changes of cerebral blood flow might play an important role in the pathogenesis of brain oedema in the early stage of severe burn.

Low shear stress regulates monocyte adhesion to oxidized lipid-induced endothelial cells via an IkappaBalpha dependent pathway.

In regions of a vessel that experience low shear stress and reversing flow patterns, early features in the pathogenesis of atherosclerosis include the accumulation of oxidized LDL (OxLDL) and adhesion of monocytes to endothelial cells (EC). Here we investigated the hypothesis that low shear stress (2 dyn/cm2) and OxLDL are synergistic for enhanced expression of vascular cell adhesion molecule (VCAM-1) and human aortic endothelial cell (HAEC)-monocyte adhesion. This study shows low shear stress can significantly reduce IkappaBalpha levels, activate NF-kappaB, increase the expression of VCAM-1 in HAEC and binding of monocytes. OxLDL itself cannot significantly increase the expression of VCAM-1 in HAEC and binding of monocytes, but through activation of NF-kappaB and degradation of IkappaBalpha induced by low shear stress it can significantly enhance VCAM-1 expression and monocyte adhesion, over that in unmodified LDL or control. These results suggest that low shear stress can regulate monocyte adhesion to oxidized lipid-induced endothelial cells via an IkappaBalpha-dependent pathway, and that low shear stress together with OxLDL may likely play an important role in atherogenesis.

The zinc finger protein A20 protects endothelial cells from burns serum injury.

Burn injuries as well as skin damages are often associated with immune suppression and often cause multiple organ failures. The monolayer endothelium is vulnerable to injuries from circulating factors resulting from remote wounds. Endothelial cell activation and apoptosis can alter microvascular permeability and intensify organ damage. A20, as a physiological cytoprotective gene is essential for preventing spontaneous innate immune cell-mediated inflammation and tissue destruction. It is not known whether A20 has the function to protect endothelial cells from the effect of burns serum challenge on endothelial function in vitro. This study shows that A20 can express in endothelial cells after burns serum stimulation and inhibit endothelial cell activation and apoptosis induced by burns serum. These results suggest that A20 may be beneficial in limiting the response to burn injuries.

[Protective effect of exogenous bcl-2 on spinal cord motoneurons following sciatic nerve axotomy in the rat].

The aim of this study was to investigate the protective effect of exogenous bcl-2 on spinal cord motoneurons following sciatic nerve axotomy. After epineurium suturing, sense bcl-2 (Ad/s-bcl-2), antisense bcl-2 (Ad/as-bcl-2), or reporter gene lacZ (Ad/lacZ) recombinant adenovirus or NS was injected into the sciatic nerve 0.5 cm distant from the sutured point respectively in different groups. The rats were transcardially perfused with 4% paraformaldehyde on postoperative 48 h, 7 d, 15 d and 30 d respectively and the spinal cords of L4 to L6 were harvested. X-gal staining, bcl-2 in situ hybridization and immunohistochemical staining, TUNEL (terminal deoxynucleotidyl transferase mediated dUTP nick end labeling) staining and AChE (acetyl cholinesterase) histochemical staining were used. We observed that the exogenous lacZ gene was expressed in the spinal cord of Ad/lacZ group, and sense bcl-2 significantly decreased the number of apoptotic motoneurons and the decreasing degree of AChE activity of the motoneurons in the spinal cord induced by sciatic nerve axotomy and accelerate AChE activity recovery. However, antisense bcl-2 increased the number of apoptotic motoneurons and the decreasing degree of AChE activity of the motoneurons in the spinal cord induced by sciatic nerve axotomy and prolonged AChE activity recovery. These results demonstrate that exogenous bcl-2 may protect motor neurons from injury induced by peripheral nerve axotomy.

[Anatomy of heart in banna mini-pig inbred-lines].

OBJECTIVE: To observe the heart anatomic and histological structure of the Banna mini-pig inbred-lined and to provide the morphological data for heart xenotransplantation and breeding transgens pig. METHODS: Ten Banna mini-pigs (12-18 months old) were affused and fixed by common coratid artery. The heart were observed and measured by gross anatomy and histology. RESULTS: There were many similarities between the Banna pig heart and the human heart in anatomy and histology. However, the following differences were observed in the Banna pig heart: 1. Azygos vein directly drew into right atrium cordis. 2. The intercalated disk of cardiac muscle was less than that of human. 3. The Purkinje's fibre was bigger than that of human. CONCLUSION: On the morphology and histology, the structure of Banna pig heart is similar to the heart of human being. It is possible that Banna minipig heart becomes organ donors for xenotransplantation.