Ding-Jun Hao

Biological roles of olfactory ensheathing cells in facilitating neural regeneration: a systematic review.

Continuous renewal of neurons throughout life in the olfactory system is often thought to be partially attributable to specialized glial cells called olfactory ensheathing cells (OECs). Hitherto, several studies have demonstrated that transplantation of OECs is one of the most promising strategies available to augment axonal regeneration and functional recovery following damage to the nervous system, including spinal cord injury (SCI). Based on these studies, a number of pre-clinical studies worldwide have been initiated using autologous transplantation of OECs into damaged central and peripheral nervous systems. Although OECs play a major role in promotion of neuron regeneration of the injured central nervous system (CNS), especially to SCI, limited valuable information is available regarding the beneficial characteristics of OECs in facilitating neural regeneration. Moreover, an increasing number of controversial issues related to the biology of OECs and their transplantation must be addressed. This step is important to better understand the cellular and molecular mechanisms modulated by transplanted OECs. To start shedding light into these controversial issues, this paper provides a systematic review regarding OECs’ beneficial roles in neural regeneration, and the unique properties of these cells that may exert a potential advantage over other cellular transplants.

Repair of spinal cord injury by implantation of bFGF-incorporated HEMA-MOETACL hydrogel in rats.

There is no effective strategy for the treatment of spinal cord injury (SCI). An appropriate combination of hydrogel materials and neurotrophic factor therapy is currently thought to be a promising approach. In this study, we performed experiments to evaluate the synergic effect of implanting hydroxyl ethyl methacrylate [2-(methacryloyloxy)ethyl] trimethylammonium chloride (HEMA-MOETACL) hydrogel incorporated with basic fibroblast growth factor (bFGF) into the site of surgically induced SCI. Prior to implantation, the combined hydrogel was surrounded by an acellular vascular matrix. Sprague–Dawley rats underwent complete spinal cord transection at the T-9 level, followed by implantation of bFGF/HEMA-MOETACL 5 days after transection surgery. Our results showed that the bFGF/HEMA-MOETACL transplant provided a scaffold for the ingrowth of regenerating tissue eight weeks after implantation. Furthermore, this newly designed implant promoted both nerve tissue regeneration and functional recovery following SCI. These results indicate that HEMA-MOETACL hydrogel is a promising scaffold for intrathecal, localized and sustained delivery of bFGF to the injured spinal cord and provide evidence for the possibility that this approach may have clinical applications in the treatment of SCI.

Phagocytic Removal of Neuronal Debris by Olfactory Ensheathing Cells Enhances Neuronal Survival and Neurite Outgrowth via p38MAPK Activity

Compelling evidence from animal models and clinical studies suggest that transplantation of olfactory ensheathing cells (OECs), specialized glia in the olfactory system, combined with specific training may be therapeutically useful in the central nervous system (CNS) injuries and neurodegenerative diseases. The unique function of OECs could mainly attribute to both production of cell adhesion molecules and secretion of growth factors in OECs, which support neuron survival and neurite outgrowth. However, little is known about whether engulfment of neuronal degenerative debris by OECs also equally contributes to neuronal survival and neurite outgrowth. Furthermore, the molecular mechanisms responsible for neuronal degenerative corpses removal remain elusive. Here, we used an in vitro model of primary culture of spinal cord neurons to investigate the effect of engulfment of degenerative neuron debris by OECs on neuronal survival and neurite outgrowth and the possible molecular mechanisms. Our results showed that OECs can engulf an amount of degenerated neuron debris, and this phagocytosis can make a substantial contribution to neuron growth, as demonstrated by increased number of neurons with longer neurite length and richer neurite branches when compared with the combination of neuron debris and OEC conditioned medium (OECCM). Moreover, p38 mitogen-activated protein kinase (p38MAPK) signaling pathway may mediate the OEC engulfment of debris because the p38MAPK-specific inhibitor, SB203580, can abrogate all the positive effects of OECs, including clearance of degenerated neuron debris and generation of bioactive molecules, indicating that p38MAPK is required for the process of phagocytosis of the neuron debris. In addition, the OEC phagocytic activity had no influence on its generation of bioactive molecules. Therefore, these findings provide new insight into further investigations on the OEC role in the repair of traumatic CNS injury and neurodegenerative diseases.

Natural products for treatment of bone erosive diseases: The effects and mechanisms on inhibiting osteoclastogenesis and bone resorption

Excessive bone resorption plays a central role on the development of bone erosive diseases, including osteoporosis, rheumatoid arthritis, and periodontitis. Osteoclasts, bone-resorbing multinucleated cells, are differentiated from hemopoietic progenitors of the monocyte/macrophage lineage. Regulation of osteoclast differentiation is considered an effective therapeutic target to the treatment of pathological bone loss. Natural plant-derived products, with potential therapeutic and preventive activities against bone-lytic diseases, have received increasing attention in recent years because of their whole regulative effects and specific pharmacological activities, which are more suitable for long-term use than chemically synthesized medicines. In this review, we summarized the detailed research progress on the active compounds derived from medical plants with potential anti-resorptive effects and their molecular mechanisms on inhibiting osteoclast formation and function. The active ingredients derived from natural plants that are efficacious in suppressing osteoclastogenesis and bone resorption include flavonoids, terpenoids (sesquiterpenoids, diterpenoids, triterpenoids), glycosides, lignans, coumarins, alkaloids, polyphenols, limonoids, quinones and others (steroid, oxoxishhone, fatty acid). Studies have shown that above natural products exert the inhibitory effects via regulating many factors involved in the process of osteoclast differentiation and bone resorption, including the essential cytokines (RANKL, M-CSF), transcription factors (NFATc1, c-Fos), signaling pathways (NF-κB, MAPKs, Src/PI3K/Akt, the calcium ion signaling), osteoclast-specific genes (TRAP, CTSK, MMP-9, integrin β3, OSCAR, DC-STAMP, Atp6v0d2) and local factors (ROS, LPS, NO). The development of osteoclast-targeting natural products is of great value for the prevention or treatment of bone diseases and for bone regenerative medicine.

Therapeutic Effects of Traditional Chinese Medicine on Spinal Cord Injury: A Promising Supplementary Treatment in Future

Objective. Spinal cord injury (SCI) is a devastating neurological disorder caused by trauma. Pathophysiological events occurring after SCI include acute, subacute, and chronic phases, while complex mechanisms are comprised. As an abundant source of natural drugs, Traditional Chinese Medicine (TCM) attracts much attention in SCI treatment recently. Hence, this review provides an overview of pathophysiology of SCI and TCM application in its therapy. Methods. Information was collected from articles published in peer-reviewed journals via electronic search (PubMed, SciFinder, Google Scholar, Web of Science, and CNKI), as well as from masters dissertations, doctoral dissertations, and Chinese Pharmacopoeia. Results. Both active ingredients and herbs could exert prevention and treatment against SCI, which is linked to antioxidant, anti-inflammatory, neuroprotective, or antiapoptosis effects. The detailed information of six active natural ingredients (i.e., curcumin, resveratrol, epigallocatechin gallate, ligustrazine, quercitrin, and puerarin) and five commonly used herbs (i.e., Danshen, Ginkgo, Ginseng, Notoginseng, and Astragali Radix) was elucidated and summarized. Conclusions. As an important supplementary treatment, TCM may provide benefits in repair of injured spinal cord. With a general consensus that future clinical approaches will be diversified and a combination of multiple strategies, TCM is likely to attract greater attention in SCI treatment.

Fibroblast Growth Factor 4 Is Required but not Sufficient for the Astrocyte Dedifferentiation

Our recent studies demonstrated that mature astrocytes from spinal cord can be reprogrammed in vitro and in vivo to generate neural stem/progenitor cells (NSPCs) following treatment with conditioned medium collected from mechanically injured astrocytes. However, little is known regarding the molecular mechanisms underlying the reprogramming of astrocytes. Here, we show that fibroblast growth factor 4 (FGF4) exerts a critical role in synergistically converting astrocytes into NSPCs that can express multiple neural stem cell markers (nestin and CD133) and are capable of both self-renewal and differentiation into neurons and glia. Lack of FGF4 signals fails to elicit the dedifferentiation of astrocytes towards NSPCs, displaying a substantially lower efficiency in the reprogramming of astrocytes and a slower transition through fate-determined state. These astrocyte-derived NSPCs displayed relatively poor self-renewal and multipotency. More importantly, further investigation suggested that FGF4 is a key molecule necessary for activating PI3K/Akt/p21 signaling cascades, as well as their downstream effectors responsible for directing cell reprogramming towards NSPCs. Collectively, these findings provide a molecular basis for astrocyte dedifferentiation into NSPCs after central nervous system (CNS) injury and imply that FGF4 may be a clinically applicable molecule for in situ neural repair in the CNS disorders.

Therapeutical Strategies for Spinal Cord Injury and a Promising Autologous Astrocyte-Based Therapy Using Efficient Reprogramming Techniques

Spinal cord injury (SCI) is a traumatic event resulting in disturbances to normal sensory, motor, or autonomic functions, which ultimately impacts a patient’s physical, psychological, and social well-being. Until now, no available therapy for SCI can effectively slow down or halt the disease progression. Compared to traditional treatments, e.g., medication, surgery, and functional electrical stimulation, stem cell replacement therapy shows high potential for repair and functional plasticity. Thus, stem cell therapy may provide a promising strategy in curative treatment of SCI, specifically when considering the requirement of neuron replenishment in the spinal cord after distinct acute injuries. However, the therapeutic application of neural stem cells (NSCs) still faces enormous challenges, such as ethical issues, possible inflammatory reactions, graft rejection, and tumor formation. Therefore, it is of vital interest to identify more suitable sources of cells with stem cell potential, which might potentially be harnessed for local neural repair. Due to abovementioned possible drawbacks, these cells should be autologous. Reprogramming of astrocytes to generate the desired neuronal cell types would open the door to autologous cell transplantation and treatment of SCI without possible severe side effects. In this paper, we review the relevant therapeutic strategies for SCI, and conversion of astrocyte into NSCs, suggesting this procedure as a possible treatment option.

Application of bee venom and its main constituent melittin for cancer treatment

Bee venom and its main constituent melittin (MEL) have been extensively studied in the treatment of tumors. However, the non-specific cytotoxicity and hemolytic activity have hampered the clinical application. Currently, a number of research groups have reported a series of optimization strategies, including gene therapy, recombinant immunotoxin incorporating MEL or MEL nanoparticles, targeting tumor cells to attenuate the cytotoxicity and improve its antitumor efficiency and therapeutic capabilities, which have shown very promising in overcoming some of these obstacles. In this review, we summarize the current knowledge regarding anticancer effects of bee venom and its main compound MEL on different kinds of tumor cells as well as elucidate their possible anticancer mechanisms. It could be concluded that MEL exerts multiple effects on cellular functions of cancerous cells such as proliferation, apoptosis, metastasis, angiogenesis as well as cell cycle, and the anticancer processes involve diverse signal molecules and regulatory pathways. We also highlight the recent research progress for efficient delivery of MEL peptide, thus providing new ideas and hopeful strategies for the in vivo application of MEL.

MicroRNA-Mediated Reprogramming of Somatic Cells into Neural Stem Cells or Neurons

Cellular reprogramming is a promising strategy to generate neural stem cells (NSCs) or desired subtype-specific neurons for cell-based therapeutic intervention. By far, the intricate cell event like reprogramming of non-neural cells to desired cell types can be achieved by forced expression of lineage-related transcription factors (TFs), nuclear transfer, a defined set of factors, and via non-coding microRNAs (miRNAs), as well as other precisely defined conditions. In addition, scientists have been trying to develop better approaches for reprogramming, either by using distinct combinations of a set of small molecules and certain TFs or delivery of appropriate small molecules and miRNAs. The miRNA-mediated approach is fascinating because of its potential to rapidly generate a variety of therapeutically desired cell types from other cell lineages. Recent studies have made great progress in miRNA-mediated neural reprogramming of somatic cells to various specific neuronal subtypes with more efficiency even though the exact mechanisms remain to be further explored. Based on key roles of miRNAs in neural reprogramming across differentiated cell lineages, it is of vital interest to summarize the recent knowledge regarding the instructive role of miRNAs in direct conversion of somatic cells into neural lineages. This precise review mainly focuses on recent discoveries of miRNAs functions in initiating cell reprogramming and fate specification of the neuronal subtype. Moreover, we discuss most recent findings about some miRNAs’ activity in regulating various developmental stages of neurons, which is helpful for understanding the event network between miRNAs and their targets.

An Alternative Long-Term Culture System for Highly-Pure Mouse Spermatogonial Stem Cells

Increasing evidence suggests that spermatogonial stem cells (SSCs) have great clinical potential to give rise to a variety of cell types besides all spermatogenic lineage cells. The development of an efficient method for long‐term culture of highly‐pure SSCs is essential for further studies related to SSC biological events. Here, we describe an in vitro culture system obtaining mouse SSC cultures of high purity, viability, and proliferation. For establishing long‐term cultures of SSCs, we mainly focused on isolation procedures and culture conditions. These included co‐coating of extracellular substrates, that is, poly‐L‐lysine (PLL) and laminin, as well as combinatiorial use of three milder enzymes and simultaneously less trypsin to minimize enzyme‐mediated degradation of SSCs. Furthermore, a unique purification procedure was performed to effectively eliminate contaminating non‐SSCs. Finally, a critical step is to ensure SSC maintenance and expansion by utilizing optimal culture medium. Obtained data suggest that applying our optimally modified method, SSCs can be cultured for over 90u2009days with high purity (around 93.5%). Moreover, SSCs isolated and expanded using our protocol fulfills all criteria of SSCs without losing their stemness‐characterized by SSC‐phenotypic gene expression and long‐term self‐renewal. This study describes for the first time a protocol allowing isolation and expansion of SSCs suitable for numerous studies related to SSC‐based clinical therapies of various diseases. J. Cell. Physiol. 230: 1365–1375, 2015.