Mao Pang

Tissue-engineered regeneration of completely transected spinal cord using induced neural stem cells and gelatin-electrospun poly (lactide-co-glycolide)/polyethylene glycol scaffolds.

Tissue engineering has brought new possibilities for the treatment of spinal cord injury. Two important components for tissue engineering of the spinal cord include a suitable cell source and scaffold. In our study, we investigated induced mouse embryonic fibroblasts (MEFs) directly reprogrammed into neural stem cells (iNSCs), as a cell source. Three-dimensional (3D) electrospun poly (lactide-co-glycolide)/polyethylene glycol (PLGA-PEG) nanofiber scaffolds were used for iNSCs adhesion and growth. Cell growth, survival and proliferation on the scaffolds were investigated. Scanning electron microcopy (SEM) and nuclei staining were used to assess cell growth on the scaffolds. Scaffolds with iNSCs were then transplanted into transected rat spinal cords. Two or 8 weeks following transplantation, immunofluorescence was performed to determine iNSC survival and differentiation within the scaffolds. Functional recovery was assessed using the Basso, Beattie, Bresnahan (BBB) Scale. Results indicated that iNSCs showed similar morphological features with wild-type neural stem cells (wt-NSCs), and expressed a variety of neural stem cell marker genes. Furthermore, iNSCs were shown to survive, with the ability to self-renew and undergo neural differentiation into neurons and glial cells within the 3D scaffolds in vivo. The iNSC-seeded scaffolds restored the continuity of the spinal cord and reduced cavity formation. Additionally, iNSC-seeded scaffolds contributed to functional recovery of the spinal cord. Therefore, PLGA-PEG scaffolds seeded with iNSCs may serve as promising supporting transplants for repairing spinal cord injury (SCI).

Effects of Salvia miltiorrhiza on neural differentiation of induced pluripotent stem cells.

ETHNOPHARMACOLOGICAL RELEVANCE Salvia miltiorrhiza, a well-known traditional Chinese medicine, is commonly used to treat some neurological diseases because of its anti-oxidative, anti-inflammatory and anti-apoptotic properties. We investigate whether Salvia miltiorrhiza can improve the differentiation of induced pluripotent stem cells (iPSCs) into neurons in vitro, and promote iPSCs-derived neural stem cells survival, integrate, and differentiation after their transplantation to the ischemic brain tissues. MATERIALS AND METHODS Induced pluripotent stem cells were used to differentiate into neural stem cells, and further into neurons in induction medium with various concentrations of Salvia miltiorrhiza. The effects were assessed by immunofluorescence staining, quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and Western blotting. iPSC-derived neural stem cells were transplanted into the brains of rats with middle cerebral artery occlusion, immunofluorescence staining was used to evaluate survival, integrate, and differentiation of grafted cells, the functional recovery of the animals was tested by the Longa scores and spontaneous motor activity. RESULTS Salvia miltiorrhiza (5μg/ml) significantly increased the gene and protein expression of Nestin compared with that in other groups. Microtubule-associated protein 2 (MAP2) expression in induction medium with 5μg/ml Salvia miltiorrhiza was significantly higher than that in the control group. After cells transplantation into the ischemic brain, more grafted MAP2(+) cells were found in Salvia miltiorrhiza-treated rats than others at 7 days. Salvia miltiorrhiza-treated rats showed the most remarkable functional recovery at 7 and 14 days. CONCLUSION Salvia miltiorrhiza induces differentiation of induced pluripotent stem cells to differentiate into neurons efficiently. The plant provides neuroprotection to implanted cells and improves functional recovery after their transplantation to the ischemic brain tissues.

Effects and mechanisms of melatonin on neural differentiation of induced pluripotent stem cells.

Melatonin, a lipophilic molecule mainly synthesized in the pineal gland, has properties of antioxidation, anti-inflammation, and antiapoptosis to improve neuroprotective functions. Here, we investigate effects and mechanisms of melatonin on neural differentiation of induced pluripotent stem cells (iPSCs). iPSCs were induced into neural stem cells (NSCs), then further differentiated into neurons in medium with or without melatonin, melatonin receptor antagonist (Luzindole) or Phosphatidylinositide 3 kinase (PI3K) inhibitor (LY294002). Melatonin significantly promoted the number of neurospheres and cell viability. In addition, Melatonin markedly up-regulated gene and protein expression of Nestin and MAP2. However, Luzindole or LY294002 attenuated these increase. The expression of pAKT/AKT were increased by Melatonin, while Luzindole or LY294002 declined these melatonin-induced increase. These results suggest that melatonin significantly increased neural differentiation of iPSCs via activating PI3K/AKT signaling pathway through melatonin receptor.

Proteins Reprogramming: Present and Future

Induced pluripotent stem cells (iPSCs) are of great clinical interest for they are derived from ones own somatic cells and have the potential of committed differentiation without immunological rejection after autografting. However, the use of viral and other modified vectors may still cause tumorigenesis due to chromosome insertion mutation, leading to limited practical use. iPSCs generated by reprogramming proteins overcome the potential safety risk and complicated manipulation procedures, thus they own better application prospective, yet some technical difficulties need to be studied and resolved, for instance, low reprogramming efficiency, unclear transduction, and reprogramming mechanism. In this paper, we summarize the current progress of proteins reprogramming technology for generation of iPSCs and discuss the promising efficiency-improved reprogramming methods by proteins plus other kinds of chemical compounds.

Interaction of iPSC-derived neural stem cells on poly(L-lactic acid) nanofibrous scaffolds for possible use in neural tissue engineering

Tissue engineering is a rapidly growing technological area for the regeneration and reconstruction of damage to the central nervous system. By combining seed cells with appropriate biomaterial scaffolds, tissue engineering has the ability to improve nerve regeneration and functional recovery. In the present study, mouse induced pluripotent stem cells (iPSCs) were generated from mouse embryonic fibroblasts (MEFs) with the non-integrating episomal vectors pCEP4-EO2S-ET2K and pCEP4-miR-302-367 cluster, and differentiated into neural stem cells (NSCs) as transplanting cells. Electrospinning was then used to fabricate randomly oriented poly(L-lactic acid) (PLLA) nanofibers and aligned PLLA nanofibers and assessed their cytocompatibility and neurite guidance effect with iPSC-derived NSCs (iNSCs). The results demonstrated that non-integrated iPSCs were effectively generated and differentiated into iNSCs. PLLA nanofiber scaffolds were able to promote the adhesion, growth, survival and proliferation of the iNSCs. Furthermore, compared with randomly oriented PLLA nanofibers, the aligned PLLA nanofibers greatly directed neurite outgrowth from the iNSCs and significantly promoted neurite growth along the nanofibrous alignment. Overall, these findings indicate the feasibility of using PLLA nanofiber scaffolds in combination with iNSCs in vitro and support their potential for use in nerve tissue engineering.

Percutaneous transforaminal endoscopic discectomy compared with microendoscopic discectomy for lumbar disc herniation: 1-year results of an ongoing randomized controlled trial

OBJECTIVE A prospective randomized controlled study was conducted to clarify whether percutaneous transforaminal endoscopic discectomy (PTED) results in better clinical outcomes and less surgical trauma than microendoscopic discectomy (MED). METHODS In this single-center, open-label, randomized controlled trial, patients were included if they had persistent signs and symptoms of radiculopathy with corresponding imaging-confirmed lumbar disc herniation. Patients were randomly allocated to the PTED or the MED group by computer-generated randomization codes. The primary outcome was the Oswestry Disability Index (ODI) score 1 year after surgery. Secondary outcomes included scores of the Medical Outcomes Study 36-Item Short-Form Health Survey bodily pain and physical function scales, EuroQol Groups EQ-5D , and the visual analog scales for back pain and leg pain. Data including duration of operation, in-bed time, length of hospital stay, surgical cost and total hospital cost, complications, and reoperations were recorded. RESULTS A total of 153 participants were randomly assigned to 2 treatment groups (PTED vs MED), and 89.5% (137 patients) completed 1 year of follow-up. Primary and secondary outcomes did not differ significantly between the treatment groups at each prespecified follow-up point (p > 0.05). For PTED, there was less postoperative improvement in ODI score in the median herniation subgroup at 1 week (p = 0.027), 3 months (p = 0.013), 6 months (p = 0.027), and 1 year (p = 0.028) compared with the paramedian subgroup. For MED, there was significantly less improvement in ODI score at 3 months (p = 0.008), 6 months (p = 0.028), and 1 year (p = 0.028) in the far-lateral herniation subgroup compared with the paramedian subgroup. The total complication rate over the course of 1 year was 13.75% in the PTED group and 16.44% in the MED group (p = 0.642). Five patients (6.25%) in the PTED group and 3 patients (4.11%) in the MED group suffered from residue/recurrence of herniation, for which reoperation was required. CONCLUSIONS Over the 1-year follow-up period, PTED did not show superior clinical outcomes and did not seem to be a safer procedure for patients with lumbar disc herniation compared with MED. PTED had inferior results for median disc herniation, whereas MED did not seem to be the best treatment option for far-lateral disc herniation. Clinical trial registration no.: NCT01997086 (clinicaltrials.gov).

Effects and mechanisms of matrix metalloproteinase2 on neural differentiation of induced pluripotent stem cells

Induced pluripotent stem cells (iPSCs) possess the potential to differentiate into neural lineage cells. Matrix metalloproteinase 2 (MMP2), an endopeptidase in the extracellular matrix, has been shown to protect neural cells from injury. However, the mechanisms and effects of MMP2 on neural differentiation of iPSCs remain poorly understood. Here, we demonstrated a role for MMP2 in the differentiation of iPSCs to neurons via the AKT pathway. Treatment of iPSCs with MMP2 promoted their proliferation and differentiation into neural stem cells (NSCs), and then into neurons. The transcript and protein expression of Nestin and microtubule-associated protein 2 (MAP2) increased. Moreover, MMP2 markedly induced the expression of phospho-AKT (pAKT) during these differentiation stages. Consistently, silencing MMP2 using siRNA attenuated the expression of Nestin, MAP2 and pAKT, compared with the control group. In addition, the increasing levels of Nestin, MAP2 and pAKT in the MMP2 group were declined by pretreatment with the phosphoinositide 3-kinase (PI3K)/AKT inhibitor, LY294002. Furthermore, the study detected that TrkA and TrkB were perhaps the potential receptors for these effects of MMP2 on neural differentiation through PI3K/AKT signaling pathway. Taken together, these results suggest that MMP2 induces the differentiation of iPSCs into neurons by regulating the AKT signaling pathway.

Perineurium-like sheath derived from long-term surviving mesenchymal stem cells confers nerve protection to the injured spinal cord

The functional multipotency enables mesenchymal stem cells (MSCs) promising translational potentials in treating spinal cord injury (SCI). Yet the fate of MSCs grafted into the injured spinal cord has not been fully elucidated even in preclinical studies, rendering concerns of their safety and genuine efficacy. Here we used a rat spinal cord transection model to evaluate the cell fate of allograft bone marrow derived MSCs. With the application of immunosuppressant, donor cells, delivered by biocompatible scaffold, survived up to 8 weeks post-grafting. Discernible tubes formed by MSCs were observed beginning 2 weeks after transplantation and they dominated the morphological features of implanted MSCs at 8 weeks post-grafting. The results of immunocytochemistry and transmission electron microscopy displayed the formation of perineurium-like sheath by donor cells, which, in a manner comparable to the perineurium in peripheral nerve, enwrapped host myelins and axons. The MSC-derived perineurium-like sheath secreted a group of trophic factors and permissive extracellular matrix, and served as a physical and chemical barrier to insulate the inner nerve fibers from ambient oxidative insults by the secretion of soluble antioxidant, superoxide dismutase-3 (SOD3). As a result, many intact regenerating axons were preserved in the injury/graft site following the forming of perineurium-like sheath. A parallel study utilizing a good manufacturing practice (GMP) grade human umbilical cord-derived MSCs or allogenic MSCs in an acute contusive/compressive SCI model exhibited a similar perineurium-like sheath formed by surviving donor cells in rat spinal cord at 3 weeks post-grafting. The present study for the first time provides an unambiguous morphological evidence of perineurium-like sheath formed by transplanted MSCs and a novel therapeutic mechanism of MSCs in treating SCI.

Microendoscopy-Assisted Minimally Invasive Versus Open Transforaminal Lumbar Interbody Fusion for Lumbar Degenerative Diseases: 5-Year Outcomes

OBJECTIVE We sought to evaluate 5-year outcomes between microendoscopy-assisted minimally invasive (MIS) and open transforaminal lumbar interbody fusion (TLIF). METHODS Sixty single-level MIS and open surgeries were performed (30 patients in either group). Perioperative parameters including operative duration, intraoperative estimated blood loss, fluoroscopy time, postoperative analgesic usage, ambulatory time, and complications were recorded. Visual analog scale (back and leg), Japanese Orthopaedics Association score, and Oswestry Disability Index were obtained. Finally, self-evaluation of surgical outcomes (modified MacNab criteria), interbody fusion rate (Bridwell grade 1), and prevalence of adjacent segment degeneration were assessed. RESULTS Intraoperative estimated blood loss and postoperative analgesia usage were reduced in the MIS group, and patients undergoing microendoscopy-assisted MIS-TLIF ambulated earlier than those receiving open TLIF postoperatively. Nevertheless, surgical duration and fluoroscopy time were prolonged in the MIS group. Complication incidences were similar in both groups. Visual analog scale (back and leg), Japanese Orthopaedics Association, and Oswestry Disability Index were improved at 1 month, 2 years, and 5 years postoperatively in both groups when compared with preoperative scores. Significant improvements in these scores were found in the MIS group at 1 month postoperatively, while at 2 years and 5 years postoperatively, both groups revealed comparable aforementioned scores. Excellent and perfect scale rating, interbody fusion rate, and adjacent segment degeneration prevalence between the groups were almost similar. CONCLUSIONS Microendoscopy-assisted MIS-TLIF is comparable with open TLIF in terms of 5-year outcomes with additional benefits of reduced intraoperative iatrogenic injury, decreased initial pain, minimized activity restrictions, and accelerated ambulation recovery after surgery.

Salvianolic acid B promotes neural differentiation of induced pluripotent stem cells via PI3K/AKT/GSK3β/β-catenin pathway

Salvianolic acid B (Sal B), a water-soluble component mainly extracted from the traditional Chinese medicine Salvia miltiorrhiza, has potential anti-inflammatory, anti-oxidative and anti-apoptotic actions to protect neural cells. Here, we explore the effects and mechanisms of Sal B on the promotion of differentiation of induced pluripotent stem cells (iPSCs) into neural stem cells (NSCs), then further into neurons. During the processes of neural differentiation of iPSCs, Sal B or a phosphatidylinositide 3 kinase (PI3K) inhibitor (LY294002) were added to the medium. Sal B substantially improved proliferation of iPSC-derived NSCs and neurons. Furthermore, Sal B significantly stimulated PI3K/AKT/GSK3 β/β-catenin pathway. However, LY294002 attenuated the Sal B-induced increase. Therefore, these outcomes suggest that Sal B markedly enhances neural differentiation of iPSCs via the PI3K/AKT/GSK3β/β-catenin pathway.