Qisheng Tang

An acellular cerebellar biological scaffold: Preparation, characterization, biocompatibility and effects on neural stem cells.

Biomaterial and regenerative medical research has diversified and developed rapidly. A biological scaffold consisting of an extracellular matrix (ECM) functions not only as a supportive material but also as a regulator of cellular functions. Although decellularized scaffolds have been widely applied for the repair of non-central nervous system (CNS) tissues, their efficacy in the CNS has not been extensively investigated. In this report, we describe a dynamic decellularization protocol that combined intracardial perfusion and a series of treatments to effectively remove the cellular components from the cerebellum, which is a unique and relatively simple CNS structure. The resulting cerebellar scaffold retained neurosupportive proteins and growth factors and, when tested with neural stem cells (NSCs) in vitro, was found to be cytocompatible and to stimulate the proliferation and migration of these cells. NSCs that were cultured in vitro on the scaffold differentiated into neurons and astrocytes, as indicated by their expression of βIII-tubulin and glial fibrillary acidic protein (GFAP). Through subcutaneous and intracranial implantation experiments, this preliminary study demonstrated the in vivo biocompatibility of the cerebellar scaffold and indicated its potential for future applications. Thus, our study demonstrated that the cerebellar ECM scaffold provided tissue-specific advantages for regenerative medical applications.

Current status of cell-mediated regenerative therapies for human spinal cord injury

During the past decade, significant advances have been made in refinements for regenerative therapies following human spinal cord injury (SCI). Positive results have been achieved with different types of cells in various clinical studies of SCI. In this review, we summarize recently-completed clinical trials using cell-mediated regenerative therapies for human SCI, together with ongoing trials using neural stem cells. Specifically, clinical studies published in Chinese journals are included. These studies show that current transplantation therapies are relatively safe, and have provided varying degrees of neurological recovery. However, many obstacles exist, hindering the introduction of a specific clinical therapy, including complications and their causes, selection of the target population, and optimization of transplantation material. Despite these and other challenges, with the collaboration of research groups and strong support from various organizations, cell-mediated regenerative therapies will open new perspectives for SCI treatment.

Towards retinal ganglion cell regeneration.

Traumatic optic nerve injury and glaucoma are among the leading causes of incurable vision loss across the world. What is worse, neither pharmacological nor surgical interventions are significantly effective in reversing or halting the progression of vision loss. Advances in cell biology offer some hope for the victims of optic nerve damage and subsequent partial or complete visual loss. Retinal ganglion cells (RGCs) travel through the optic nerve and carry all visual signals to the brain. After injury, RGC axons usually fail to regrow and die, leading to irreversible loss of vision. Various kinds of cells and factors possess the ability to support the process of axon regeneration for RGCs. This article summarizes the latest advances in RGC regeneration.

Neural stem/progenitor cells on collagen with anchored basic fibroblast growth factor as potential natural nerve conduits for facial nerve regeneration

Introducing neural stem/progenitor cells (NS/PCs) for repairing facial nerve injuries could be an alternative strategy for nerve gap reconstruction. However, the lack of success associated with current methods of applying NS/PCs to neurological disease is due to poor engraftment following transplantation into the host tissue. In this work, we developed rat-tail collagen-based nerve conduits to repair lengthy facial nerve defects, promoting NS/PC proliferation in the natural nerve conduits with anchored bFGF to improve the therapeutic effects of cell transplantation. In vitro studies showed that heparinized collagen prevented leakage of bFGF and NS/PCs expended in the rat-tail collagen gel with the anchored bFGF. The natural nerve conduits were implanted to connect 8-mm facial nerve defects in rats. The repair outcomes including vibrissae movements, electrophysiological tests, immunohistochemistry and remyelination analysis of regenerated nerve were evaluated. At 12weeks after implantation, only natural nerve conduits treated group showed Hoechst labeled NS/PCs. Besides, the natural nerve conduit significantly promoted functional recovery and nerve growth, which was similar to those of the gold standard, an autograft. The animal experiment results suggesting that the natural nerve conduits were valuable for facial nerve reconstruction. STATEMENT OF SIGNIFICANCE Neural stem/progenitor cells (NS/PCs) were beneficial for the treatment of nervous system diseases. However, after transplantation, the beneficial was limited because the number of living NS/PCs decreased rapidly due to insufficient signaling molecules, such as growth factors, in the microenvironments surrounding transplanted cells. In the present study, we constructed collagen-based nerve conduit with anchored bFGF to achieve higher numbers of NS/PCs for repairing facial nerve injury. Compared with other methods involving neutral salt treatment or dialysis, the fabrication method of collagen scaffolds was simple, low-cost and safe, requiring a relatively short time to prepare. At 12weeks after transplantation, the functional and histological results of natural nerve conduits treated group showed significant similarities to the gold standard method of nerve autografting.

Sustained delivery of glial cell-derived neurotrophic factors in collagen conduits for facial nerve regeneration

Facial nerve injury caused by traffic accidents or operations may reduce the quality of life in patients, and recovery following the injury presents unique clinical challenges. Glial cell-derived neurotrophic factor (GDNF) is important in nerve regeneration; however, soluble GDNF rapidly diffuses into body fluids, making it difficult to achieve therapeutic efficacy. In this work, we developed a rat tail derived collagen conduit to connect nerve defects in a simple and safe manner. GDNF was immobilized in the collagen conduits via chemical conjugation to enable controlled release of GDNF. The GDNF delivery system prevented rapid diffusion from the site without impacting bioactivity of GDNF; degradation of the collagen conduit was inhibited owing to the chemical conjugation. The artificial nerve conduit was then used to examine facial nerve regeneration across a facial nerve defect. Following transplantation, the artificial nerve conduits degraded gradually without causing dislocations and serious inflammation, with good integration into the host tissue. Functional and histological tests indicated that the artificial nerve conduits were able to guide the axons to grow through the defect, reaching the distal stumps. The degree of nerve regeneration in the group that was treated with the artificial nerve conduit approached that of the autograft group, and exceeded that of the other conduit grafted groups. STATEMENT OF SIGNIFICANCE In this study, we developed artificial nerve conduits consisting of GDNF immobilized on collagen, with the aim of providing an environment for nerve regeneration. Our results show that the artificial nerve conduits guided the regeneration of axons to the distal nerve segment. GDNF was immobilized stably in the artificial nerve conduits, and therefore retained a sufficient concentration at the target site to effectively promote the regeneration process. The artificial nerve conduits exhibited good biocompatibility and facilitated nerve regeneration and functional recovery with an efficacy that was close to that of an autograft, and better than that of the other conduit grafted groups. Our approach provides an effective delivery system that overcomes the rapid diffusion of GDNF in body fluids, promoting peripheral nerve regeneration. The artificial nerve conduit therefore qualifies as a putative candidate material for the fabrication of peripheral nerve reconstruction devices.

BCNU/PLGA microspheres: a promising strategy for the treatment of gliomas in mice

OBJECTIVE To investigate the effects of BCNU/PLGA microspheres on tumor growth, apoptosis and chemotherapy resistance in a C57BL/6 mice orthotopic brain glioma model using GL261 cell line. METHODS BCNU/PLGA sustained-release microspheres were prepared by the water-in-oil-in-water emulsion technique. GL261 cells were intracranially injected into C57BL/6 mouse by using the stereotactic technology. A total of 60 tumor-bearing mice were randomly and equally divided into three groups: untreated control, PLGA treated, BCNU/PLGA treated. Magnetic resonance imaging (MRI) was taken to evaluate tumor volume. BCNU/PLGA sustained-release wafers were implanted in the treatment group two weeks after inoculation. Survival time and quality were observed. Specimens were harvested, and immunohistochemical staining was used to check the expression of Bax, Bcl-2, and O(6)-methylguanine-DNA methyltransferase (MGMT). Statistical methods was used for analysis of relevant data. RESULTS BCNU/PLGA sustained-release wafers were fabricated and implanted successfully. There is statistical difference of survival time between the BCNU/PLGA treated group and control groups (P<0.05). MRI scan showed inhibitory effect of BCNU/PLGA on tumor growth. Compared to the group A and B, BCNU/PLGA decreased the expression of apoptosis related gene Bcl-2 (P<0.05), but did not elevate the expression level of Bax (P>0.05), with the ratio of Bax/Bcl-2 increased. For MGMT protein expression, no statistically significant change was found in treated group (P>0.05). CONCLUSIONS Local implantation of BCNU/PLGA microspheres improved the survival quality and time of GL261 glioma-bearing mice significantly, inhibited the tumor proliferation, induced more cell apoptosis, and did not increase the chemotherapy resistance.