Search

To develop a collagen-based wound targeting repair system, we introduced two collagen-binding domains (CBDs) into the human basic fibroblast growth factor (bFGF). Three expression vectors were constructed: the first one (named V-bFGF) contained bFGF and the CBD WREPSFCALS derived from von Willeband's factor (vWF); the second (named C-bFGF) contained bFGF and the CBD TKKTLRT derived from collagenase; the third (named bFGF) was bFGF as a control. The recombinant proteins of V-bFGF and C-bFGF were demonstrated to retain both growth factor activity and collagen-binding activity. We found that C-bFGF possessed higher collagen-binding ability than V-bFGF. The targeted repair systems consisting of collagen scaffolds and CBD-bFGFs were assembled in vitro and then implanted subcutaneously. Results showed that C-bFGF promoted vascularization at the implanted sites more effectively than V-bFGF. Histological analysis showed more cells migrated into collagen scaffolds incorporated with C-bFGF than those with V-bFGF. These data suggested that the higher collagen-binding ability the CBD-bFGF possessed, the more significant vascularization, and cellularization were observed. In summary, CBD-bFGF/collagen system could be used as a targeted repair system with beneficial effects of the restriction of bFGF diffusion, the prolonging of bFGF activity, and the targeted promotion of vascularization and cellularization.

Surgical resection of deep intracranial tumors under image guidance has significant challenges. The surgeon cannot see beyond the line of sight and it is also difficult to avoid the functional nerves along the path. In this context, the design of a Minimally Invasive Neurosurgical Intracranial Robot (MINIR-II) under continuous MRI is critical. The primary goal of the overall procedure is to avoid critical brain structures to reach the tumor location. Upon reaching the tumor location, the electro-cautery at the robot tip should be controlled to resect the tumor. The new MINIR-II proposed in this work, though not yet MRI compatible, is a dexterous serial chain tendon-driven robot with larger inner space, smaller outer diameter, and less coupling effect of the tendons during actuation. Each joint of the robot was attached with two tendons and they were routed outside the robot around a pulley to achieve rotational degree of freedom. The four-joint assembled robot was manufactured using a rapid prototyping machine and was tested by an experimental setup to demonstrate the motion of the robot.Copyright © 2014 by ASME

This paper discusses the design of the mechanical structure of a quadruped robot and a three-dimensional simulation model is built under Adams simulating the mechanism's motion to capture the dynamic characteristics of the quadruped robot. This paper analyses the effect of the length of legs on the walking structure from different aspects: its movement speed, capability of climbing obstacles and the workspace of its foot end. In addition, to achieve the optimization target of balancing the output force of each hydraulic cylinder, the paper establishes a mathematical model under required constraints working out the lever members that accommodated with the structure. Synthesizing all these factors, the most satisfied structural parameters of the autonomous quadruped robot are selected.

Both T-helper 17 cells (Th-17) and CD4(+)CD25(+) regulatory T cells (Tregs) play important roles in the pathogenesis of hepatitis B virus (HBV) infection. Recent studies have suggested that Th-17 and Treg cells are increased in patients with chronic hepatitis B (CHB). This study further characterizes Th-17 and Treg cells in the blood of HBV-associated acute-on-chronic liver failure (ACLF) patients, and aids our understanding of how the two subsets of CD4(+) T cells affect each other and contribute to survival. Blood samples were obtained from 30 patients with HBV-associated ACLF, 30 patients with CHB, and 30 normal controls (NC). The frequencies of Th-17 and Treg cells were determined by intracellular cytokine staining analysis. To observe the suppressive function of Tregs, purified CD4(+)CD25(+) Tregs from peripheral blood mononuclear cells (PBMCs) were co-cultured with CD4(+)CD25(-) T cells for 48 h, and then IFN-γ and IL-17A from the supernatants were measured by ELISA. We found that both Th-17 and FoxP3(+) Treg cells were increased in ACLF patients. IL-17A secretion by CD4(+) T cells was not regulated by Treg cells, even though Tregs exhibited significant inhibition of IFN-γ production. Most importantly, the ratio of Th-17 to Treg cells was associated inversely with the survival of ACLF patients. These findings provide new information regarding the pathogenesis of HBV-associated ACLF, and the ratio of Th-17 to Tregs may represent a potential prognostic marker for the disease.

OCT4 is a pivotal transcription factor in maintaining the pluripotency and self-renewal capacities of embryonic stem (ES) cells. Human OCT4 can generate two isoforms by alternative splicing, termed OCT4A and OCT4B. OCT4A confers the stemness properties of ES cells, whereas the function of OCT4B is unknown. We present here the diverse protein products and a novel function of OCT4 gene. A single OCT4B mRNA can encode three isoforms by alternative translation initiation at AUG and CUG start codons, respectively. A putative internal ribosome entry site (IRES) has been identified in OCT4B mRNA accounting for the translation mechanism. The OCT4B-190 is upregulated under stress conditions and it may protect cell against apoptosis under stress. This work evokes the significance to distinguish the biological function of the protein products of OCT4. The OCT4 gene, by the regulation of alternative splicing and alternative translation initiation, may carry out more crucial roles in many biological events. Disclosure of potential conflicts of interest is found at the end of this article.

Growth factors such as brain-derived neurotrophic factor (BDNF) are widely used in the recovery of spinal cord injury (SCI) for promoting axonal regeneration or improving neuron survival. However, the lack of efficient delivery approaches limits their clinical applications. In this study, we constructed an efficient delivery system including collagen-binding BDNF and linear ordered collagen scaffolds (LOCS). A collagen-binding domain (CBD) was utilized to construct collagen-targeting BDNF (CBD-BDNF) to allow its specific binding to the collagen. In vitro activity assay showed that CBD-BDNF had similar bioactivity in neurite outgrowth of dorsal root ganglia and the survival of PC12 cells. CBD-BDNF was shown to have specific binding activity to collagen. Using the rat hemisection SCI model, we found that LOCS loaded with CBD-BDNF significantly improved the SCI recovery evaluated by the Basso, Beattie, and Bresnahan scale and immunohistochemical staining with anti-neurofilament antibody. Thus, this targeting drug delivery system consisting of CBD-BDNF and LOCS could be an effective strategy for the repair of SCI.

Studies have shown that exogenous nerve growth factor (NGF) accelerates ulcer healing, but the inefficient growth factor delivery system limits its clinical application. In this report, we found that the native human NGF-beta fused with a collagen-binding domain (CBD) could form a collagen-based NGF targeting delivery system, and the CBD-fused NGF-beta could bind to collagen membranes efficiently. Using the rabbit dermal ischemic ulcer model, we have found that this targeting delivery system maintains a higher concentration and stronger bioactivity of NGF-beta on the collagen membranes by promoting peripheral nerve growth. Furthermore, it enhances the rate of ulcer healing through accelerating the re-epithelialization of dermal ulcer wounds and the formation of capillary lumens within the newly formed tissue area. Thus, collagen membranes loaded with collagen-targeting human NGF-beta accelerate ulcer healing efficiently.

Appropriate three-dimensional (3D) scaffolds and signal molecules could accelerate tissue regeneration and wound repair. In this work, we targeted human basic fibroblast growth factor (bFGF), a potent angiogenic factor, to a fibrin scaffold to improve therapeutic angiogenesis. We fused bFGF to the Kringle4 domain (K4), a fibrin-binding peptide from human plasminogen, to endow bFGF with specific fibrin-binding ability. The recombinant K4bFGF bound specifically to the fibrin scaffold so that K4bFGF was delivered in a site-specific manner, and the fibrin scaffold provided 3D support for cell migration and proliferation. Subcutaneous implantation of the fibrin scaffolds bound with K4bFGF but not with bFGF induced neovascularization. Immunohistochemical analysis showed significantly more proliferation cells in the fibrin scaffolds incorporated with K4bFGF than in those with bFGF. Moreover, the regenerative tissues were integrated well with the fibrin scaffolds, suggesting its good biocompatibility. In summary, targeted delivery of K4bFGF could potentially improve therapeutic angiogenesis.

Demineralized bone matrix (DBM) is a collagen-based scaffold, but its low mechanical strength and limited BMP-2 binding ability restrict its application in bone repair. It is known that heparin could be immobilized onto scaffolds to enhance their binding of growth factors with the heparin-binding domain. Here, we crosslinked heparin to DBM to increase its BMP-2 binding ability. To our surprise, the mechanical strength of DBM was also dramatically increased. The compression modulus of heparin crosslinked DBM (HC-DBM) have improved (seven-fold increased) under wet condition, which would allow the scaffolds to keep specific shapes in vivo. As expected, HC-DBM showed specific binding ability to BMP-2. Additional studies showed the bound BMP-2 exerted its function to induce cell differentiation on the scaffold. Subcutaneous implantation of HC-DBM carrying BMP-2 showed higher alkaline phosphatase (ALP) activity (2 weeks), more calcium deposition (4 and 8 weeks) and more bone formation than that of control groups. It is concluded that HC-DBM has increased mechanical intensity as well as specific BMP-2 binding ability; HC-DBM/BMP-2 enhances the osteogenesis and therefore could be an effective medical device for bone repair.

Nerve growth factor (NGF) plays a critical role in neuronal development and regeneration. However, the lack of efficient NGF delivery system limits its clinical application. We reported that a peptide deduced from collagenase, TKKTLRT, fused with NGF-β could develop a collagen based NGF targeting delivery system. Our results showed that this peptide could allow fused NGF-β bind to collagen specifically. In addition, we found that the polypeptide could result in a 2.3-fold increase in the expression level and a significant improvement of bioactivity of fused NGF-β. In the in vivo function study, collagen membranes loaded with the collagen binding NGF enhanced the nerve growth. Thus, the targeting wound repair system could be important for the repair of peripheral nerve injury. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2007

Platelet-derived growth factor BB (PDGF-BB) was an important inductive factor during wound healing, but the lack of efficient delivery system limited its clinical application. Here, a peptide of seven amino acids was firstly utilized to engineer PDGF-BB to construct a collagen-targeting system. This peptide functioned as collagen-binding domain (CBD) to specially target the PDGF-BB to the collagen and restrict its diffusion. In our study, in vitro activity assay showed that the CBD-fused PDGF (CBD-PDGF) and native PDGF (NAT-PDGF) possessed similar activity to stimulate the human fibroblast proliferation. As expected, this peptide promoted the binding of PDGF to collagen scaffolds, and CBD-PDGF caused more cells to proliferate on the collagen gel than NAT-PDGF when the same amounts of PDGF were added. In the in vivo experiment, CBD-PDGF-loaded collagen scaffolds were uniformly cellularized and vascularized compared to that of NAT-PDGF-loaded scaffolds. Our study demonstrated that the CBD targeted PDGF to the collagen scaffold to exert its functions, and it suggested this could be an effective system for targeting tissue regeneration and wound repair.

Olfactory ensheathing cell (OEC) transplantation is a promising or potential therapy for spinal cord injury (SCI). However, the effects of injecting OECs directly into SCI site have been limited and unsatisfied due to the complexity of SCI. To improve the outcome, proper biomaterials are thought to be helpful since these materials would allow the cells to grow three-dimensionally and guide cell migration. In this paper, we have studied the behavior of OECs in two-dimensional (2-D) condition as well as on three-dimensional (3-D) collagen scaffolds by analyzing their phenotypes such as cell proliferation, apoptosis, morphology, and gene activities of some neurotrophic factors and myelin proteins. OECs proliferation rate was increased on 3-D collagen scaffolds compared to the 2-D culture condition. OECs on 3-D collagen scaffolds also showed less apoptosis. In addition, OECs on 3-D collagen scaffolds maintained the original spindle-shape morphology and P75NTR gene activity. NGF, BDNF, and PLP were found to be upregulated in OECs cultured on 3-D collagen scaffolds by the semi-quantitative RT-PCR approach. The results suggested that 3-D collagen scaffolds provide suitable environments for the OECs to maintain their morphology as well as several important functional phenotypes and all these could be helpful for the effective treatment of SCI.

Background Neural stem/progenitor cells (NPCs) can differentiate into neurons, astrocytes and oligodendrocytes. NPCs are considered valuable for the cell therapy of injuries in the central nervous system (CNS). However, when NPCs are transplanted into the adult mammalian spinal cord, they mostly differentiate into glial lineage. The same results have been observed for endogenous NPCs during spinal cord injury. However, little is known about the mechanism of such fate decision of NPCs. Methodology/Principal Findings In the present study, we have found that myelin protein and Nogo-66 promoted the differentiation of NPCs into glial lineage. NgR and mTOR-Stat3 pathway were involved in this process. Releasing NgR from cell membranes or blocking mTOR-STAT3 could rescue the enhanced glial differentiation by Nogo-66. Conclusions/Significance These results revealed a novel function of Nogo-66 in the fate decision of NPCs. This discovery could have profound impact on the understanding of CNS development and could improve the therapy of CNS injuries.

A 22-year-old female presented with a 5-day history of fever,conjunctivitis, coryza, cough, nasal discharge and 1-day ofdyspnea. A maculopapular rash had appeared on her facetwo days ago and had spread to her upper torso and shoul-ders. The patient had never been vaccinated against measles.On examination, the temperature was 39.1