The influence of laminin-derived peptides conjugated to Lys-capped PLLA on neonatal mouse cerebellum C17.2 stem cells

Chemical guiding cues are being exploited to stimulate neuron adhesion and neurite outgrowth. In this study, an amino-functioned PLLA, lysine-capped PLLA [K-(CH₂)_n-PLLA (n = 2, 5, 8)], was synthesized with different length of linking spaces between lysine molecule and PLLA backbone. Drop-cast films were fabricated from K-(CH₂)_n-PLLA/PLLA blends (10/90, w/w) and amino groups were detected on the surfaces of the resultant films. More amine groups were detected on the surface and the hydrophilicity of the films was obviously improved by annealing the films in water. The representative atomic force microscopy (AFM) images indicated that incorporation of lysine-capped PLLA into PLLA matrix increased the roughness of the films and resulted in a phase separation with distinct two nano-domains which may correspond to the hydrophilic and hydrophobic domains. Furthermore, the laminin-derived peptides, CYIGSR (Cys-Tyr-Ile-Gly-Ser-Arg) and CSIKVAV (Cys-Ser-Ile-Lys-Val-Ala-Val), were jointly tethered to the amine groups of lysine-capped PLLA by a linking reagent sulfo-succinimidyl 4-(N-maleimidomethyl) cyclohexane-1-carboxylate (Sulfo-SMCC). The neonatal mouse cerebellum C17.2 stem cells were seeded on the peptides-grafted K-(CH₂)_n-PLLA/PLLA (n = 2, 5, 8) films and pure PLLA films were used as controls. Improved viability and longer neurites were obtained on the peptide-grafted films than PLLA film over the cultivation period, especially for K-(CH₂)₅-PLLA/PLLA, which had the highest peptide density of 0.28 ± 0.03 μg/cm². This study highlights the potential of using the lysine-cappeded PLLA with laminin-derived peptides for promoting nerve regeneration.     

大鼠胚胎神经干细胞与永生化神经干细胞系C17.2定向分化为神经元潜能的差异

目的 对比大鼠早期胚胎神经干细胞( NSCs)与永生化神经干细胞系C17.2(C17.2-NSC)定向分化为神经元潜能的差异,确立适用于诱导NSCs定向分化为神经元高内涵药物筛选的NSCs筛选模型. 方法 C17.2-NSC、17d胚胎海马NSCs(E17-NSC)及11d胚胎大脑皮层NSCs(E11-NSC)均设定对照组和实验组,对照组与实验组的细胞在含有2％ (v/v) B27的DMEM/F12培养液中,分别经0μmol/L和1μmol/L维甲酸(RA)在37℃、5％CO2常规培养条件下诱导分化5d,通过免疫组织化学技术检测对照组与实验组中NSCs或前体细胞特异性标志蛋白巢蛋白(Nestin)及神经元特异性标志蛋白βⅢ微管蛋白(Tuj1)表达量的差异. 结果 与对照组相比,C17.2-NSC经1μμmol/L RA诱导后未定向分化为神经元,而E17-NSC及E11-NSC经1μmol/L RA诱导后可有效定向分化为神经元. 结论 相对于C17.2-NSC,大鼠早期胚胎NSCs定向分化为神经元的潜能更强,适用于诱导NSCs定向分化为神经元的高内涵药物筛选.     

脑组织提取液促进体外培养神经干细胞增殖

目的： 寻找特异性的具有促神经干细胞分裂增殖作用的物质，为神经系统发育研究和神经系统疾病包括脑退行性疾病的治疗研究提供新资料。 方法： 制备新生鼠的前脑、中脑、后脑及小脑组织提取液，体外培养新生鼠神经干细胞，观察神经球的生长情况，采用MTT细胞活性检测法和特异性蛋白质免疫细胞化学染色鉴定神经干细胞的增殖能力。 结果： 中脑和小脑的提取液加入后有大量神经球生成，神经干细胞的特异性蛋白nestin免疫细胞化学染色呈阳性。 结论： 中脑和小脑的提取液可促进体外培养的神经干细胞增殖分裂，且呈一定量效关系。     

Effect of electron beam irradiation on the structure and properties of electrospun PLLA and PLLA/PDLA blend nanofibers

Poly(l-lactide) (PLLA) and a PLLA/poly(d-lactide) (PDLA) blend (50/50 wt.%) were electrospun into nanofibers. Electron beam (e-beam) irradiation of the electrospun PLLA and blend nanofibers was used as a method to alter their structures and surface properties. The crystalline structures of the nanofibers before and after irradiation were investigated by differential scanning calorimetry. Tensile tests of the aligned nanofibers were also performed to determine the effects of irradiation on the mechanical properties of the nanofibers. The hydrophilicity of the nanofibers was determined by water contact angle measurements, while any degradation of the fibers caused by irradiation could be detected by intrinsic viscosity measurements. The e-beam irradiation method was able to improve the surface hydrophilicity of the PLLA and blend nanofibers, although bulk degradation was inevitable.     

The effects of electrospun TSF nanofiber diameter and alignment on neuronal differentiation of human embryonic stem cells

Although transplantation of human embryonic stem cells (hESCs)-derived neural precursors (NPs) has been demonstrated with some success for nervous repair in small animal model, control of the survival, and directional differentiation of these cells is still challenging. Meanwhile, the notion that using suitable scaffolding materials to control the growth and differentiation of grafted hESC-derived NPs raises the hope for better clinical nervous repair. In this study, we cultured hESC-derived NPs on Tussah silk fibroin (TSF)-scaffold of different diameter (i.e., 400 and 800 nm) and orientation (i.e., random and aligned) to analyze the effect of fiber diameter and alignment on the cell viability, neuronal differentiation, and neurite outgrowth of hESC-derived NPs. The results show that TSF-scaffold supports the survival, migration, and differentiation of hESC-derived NPs. Aligned TSF-scaffold significantly promotes the neuronal differentiation and neurite outgrowth of hESC-derived neurons compared with random TSF-scaffold. Moreover, on aligned 400 nm fibers cell viability, neuronal differentiation and neurite outgrowth are greater than that on aligned 800 nm fibers. Together, these results demonstrate that aligned 400 nm TSF-scaffold is more suitable for the development of hESC-derived NPs, which shed light on optimization of the therapeutic potential of hESCs to be employed for neural regeneration.     

The influence of fiber diameter of electrospun substrates on neural stem cell differentiation and proliferation

Neural stem/progenitor cells (NSCs) are capable of self-renewal and differentiation into all types of neural lineage under different biochemical and topographical cues. In this study, we cultured rat hippocampus-derived adult NSCs (rNSCs) on laminin-coated electrospun Polyethersulfone (PES) fiber meshes with average fiber diameters of 283+/-45 nm, 749+/-153 nm and 1452+/-312 nm; and demonstrated that fiber diameter of PES mesh significantly influences rNSC differentiation and proliferation. Under the differentiation condition (in the presence of 1 microM retinoic acid and 1% fetal bovine serum), rNSCs showed a 40% increase in oligodendrocyte differentiation on 283-nm fibers and 20% increase in neuronal differentiation on 749-nm fibers, in comparison to tissue culture polystyrene surface. SEM imaging revealed that cells stretched multi-directionally to follow underlying 283-nm fibers, but extended along a single fiber axis on larger fibers. When cultured on fiber meshes in serum free medium in the presence of 20 ng/mL of FGF-2, rNSCs showed lower proliferation and more rounded morphology compared to that cultured on laminin-coated 2D surface. As the fiber diameter decreased, higher degree of proliferation and cell spreading and lower degree of cell aggregation were observed. This collective evidence indicates fiber topography can play a vital role in regulating differentiation and proliferation of rNSCs in culture.     

Immunosuppressive effects of mesenchymal stem cells in collagen-induced mouse arthritis

Objective  

The objective of this study was to investigate the efficacy of mesenchymal stem cell (MSC) in the treatment of arthritis.     

Enhanced differentiation of human neural crest stem cells towards the Schwann cell lineage by aligned electrospun fiber matrix

Human pluripotent stem cell-derived neural crest stem cells (NCSCs) provide a promising cell source for generating Schwann cells in the treatment of neurodegenerative diseases and traumatic injuries in the peripheral nervous system. Influencing cell behavior through a synthetic matrix topography has been shown to be an effective approach to directing stem cell proliferation and differentiation. Here we have investigated the effect of nanofiber topography on the differentiation of human embryonic stem cell-derived NCSCs towards the Schwann cell lineage. Using electrospun fibers of different diameters and alignments we demonstrated that aligned fiber matrices effectively induced cell alignment, and that fiber matrices with average diameters of 600 nm and 1.6 μm most effectively promoted NCSC differentiation towards the Schwann cell lineage compared with random fibers and two-dimensional tissue culture plates. More importantly, human NCSCs that were predifferentiated in Schwann cell medium for 2 weeks exhibited higher sensitivity to the aligned fiber topography than undifferentiated NCSCs. This study provides an efficient protocol for Schwann cell derivation by combining an aligned nanofiber matrix and an optimized differentiation medium, and highlights the importance of matching extrinsic matrix signaling with cell intrinsic programming in a temporally specific manner.     

Synergistic angiogenesis promoting effects of extracellular matrix scaffolds and adipose-derived stem cells during wound repair

Slow vascularization rate is considered one of the main drawbacks of scaffolds used in wound healing. Several efforts, including cellular and acellular technologies, have been made to induce vascular growth in scaffolds. However, thus far, there is no established technology for inducing vascular growth. The aim of this study was to promote the vascularization capacities of scaffolds by seeding adipose-derived stem cells (ADSCs) on them and to compare the vascularization capacities of different scaffolds seeded with ADSCs. Two kinds of extracellular matrix scaffolds (small intestinal submucosa [SIS] and acellular dermal matrix [ADM]) and a kind of composite scaffold (collagen-chondroitin sulfate-hyaluronic acid [Co-CS-HA]) were selected. Subcutaneous implantation analysis showed that the vascularization capacity of SIS and ADM was greater than that of Co-CS-HA. ADSCs seeded in SIS and ADM secreted greater amounts of vascular endothelial growth factor than those seeded in Co-CS-HA. In a murine skin injury model, ADSC-seeded scaffolds enhanced the angiogenesis and wound healing rate compared with the nonseeded scaffolds. Moreover, ADSC-SIS and ADSC-ADM had greater vascularization capacity than that of ADSC-Co-CS-HA. Taken together, these results suggest that ADSCs could be used as a cell source to promote the vascularization capacities of scaffolds. The vascularization capacities of ADSC-seeded scaffolds were influenced by both the vascularization capacities of the scaffolds themselves and their effects on the angiogenic potential of ADSCs; the combination of extracellular matrix scaffolds and ADSCs exhibited synergistic angiogenesis promoting effects.     

Synergistic effects of ATP on oxytocin-induced intracellular Ca2+ response in mouse mammary myoepithelial cells

An increase in intracellular Ca2+ ([Ca2+]i) is essential for mammary myoepithelial cells to contract, leading to milk ejection during lactation. In this study, the intracellular signaling leading to the increase in [Ca2+]i in cultured myoepithelial cells from mouse lactating mammary glands was investigated using fura-2 fluorescence ratiometry. [Ca2+]i increased in cultured myoepithelial cells in response to either oxytocin (1 nM) or ATP (10 microM), and the cells then contracted. These [Ca2+]i responses were diminished by treatment with an inhibitor of phospholipase C (> or = 1 microM U73122). Intracellular application of inositol 1,4,5-trisphosphate (IP3: 10 or 100 microM) increased [Ca2+]i. Pretreatment with pertussis toxin (PTX: 0.1 or 1 microgram/ml) inhibited the [Ca2+]i response to ATP, but had less of an effect on the response to oxytocin. These results indicate that oxytocin and purinergic receptors are coupled to PTX-insensitive and PTX-sensitive G proteins, respectively, and that their activation leads to the increase in [Ca2+]i through the release of Ca2+ from IP3-sensitive intracellular stores via the inositol-phospholipid signaling pathway. Furthermore, we found that the [Ca2+]i responses to oxytocin at physiological doses (0.01-0.1 nM) were augmented in the presence of a sub-responsive dose of ATP (1 microM). The activation of purinergic receptors may facilitate myoepithelial cell contraction in milk-ejection responses.     

胚胎干细胞C3B鼠视网膜下腔移植分化研究

目的：探讨胚胎干细胞在具有正常视网膜结构的C3B鼠视网膜下腔中的诱导分化情况。 方法:胚胎干细胞传1代后进行拟胚体培养。拟胚体消化成单细胞后联合视黄酸注入C3B鼠视网膜下腔，注射后1周、3周、2月处死小鼠取材进行病理切片、电镜检查和免疫组化检测。 结果:1周时，可见到注射部位视网膜层水肿增厚。3周和2个月时，3只移植眼内出现畸胎瘤，占所有移植眼的25%，其余眼球注射部位仅见瘢痕组织或眼球萎缩。电镜发现增殖的细胞核异型性明显，具肿瘤细胞特征。免疫组化显示：畸胎瘤部分区域MAP-2强阳性反应；可见团状或集落状细胞GFAP强阳性反应；个别细胞Nestin阳性反应。 结论:胚胎干细胞移植入具有正常视网膜结构的C3B鼠视网膜下腔，未能出现ESC向视网膜组织分化或嵌入视网膜组织，相当部分的鼠眼出现了畸胎瘤，其临床安全性和致瘤性是非常值得关注的问题。     

Synergistic effect of laminin and mesenchymal stem cells on tracheal mucosal regeneration

Although several studies have been successfully undertaken of tracheal reconstruction in terms of the maintaining the framework of the graft, most cases of reconstruction failure have resulted from delayed mucosal regeneration. The purposes of this study were to evaluate whether laminin-coated asymmetrically porous membrane (APM) scaffold enhances mucosal regeneration, to compare the mucosalization capability with mesenchymal stem cell (MSC) seeded APM, and to determine whether laminin coating and MSC seeding has a synergistic effect on mucosal regeneration. We reconstructed the full-thickness anterior tracheal defect of 36 New Zealand White rabbits with the APM scaffold. MSCs were isolated from the rabbit's inguinal fat. The animals were divided into 4 groups by the presence of laminin coating on APM and application of MSC [Group I, −/− (laminin/MSC); Group II, −/+; Group III, +/−; Group IV, +/+]. Endoscopy and histologic evaluation were performed and the results were compared among the groups. The results showed that ciliated columnar epithelium was regenerated earlier in groups II and III than in group I. Furthermore, the application of laminin and MSC had synergistic effects on tracheal epithelial regeneration. These results demonstrate that tracheal reconstruction by laminin-coated APM seeded with MSCs is most effective in enhancing tracheal mucosalization, and appears to be promising strategy in the regenerative treatment of tracheal defects.     

Distribution and homing pattern of c-kit+ Sca-1+ CXCR4+ resident cardiac stem cells in neonatal,postnatal, and adult mouse heart

IntroductionThe origin of heart-forming cells and their roles in organ development have fascinated biologists for over a century. C-X-C chemokine receptor type 4 plays a crucial role during embryonic development and in maintaining the stem cell niche and homing. The aim of the present was to study the expression pattern of resident cardiac stem cell markers and their homing factor in neonatal, postnatal, and adult mouse heart.MethodsCardiac stem cell protein expression was analyzed using immunofluorescence, immunohistochemistry, and Western blotting. The messenger ribonucleic acid expression of cardiac stem cell markers c-kit, stem cell antigen-1, and homing factor C-X-C chemokine receptor type 4 was quantitatively analyzed using quantitative polymerase chain reaction. Data were analyzed using Student's t test and two-way analysis using SPSS software.ResultsStem cell antigen-1- and c-kit-positive cell populations were heterogeneously distributed in the adult and postnatal hearts but scattered in the neonatal heart. The expression of c-kit showed a significant difference between right and left atrium, though it was higher compared to ventricles. The homing factor C-X-C chemokine receptor type 4 expression was higher in the neonatal heart than in the postnatal heart but was not detectable in the adult heart.ConclusionsThe present study reveals the distribution of cardiac stem cells in the different compartments of the heart and significant reduction in their number in adult heart. Cardiac stem cells are higher in the atrium than in the ventricle, suggesting the atria as the source of cardiac stem cell.     

异氟醚对新生大鼠海马神经干细胞增殖及分化的影响

BACKGROUND: Isoflurane is an anesthesia drug that has a certain effect on the nervous system. It possibly causes neurologic disorders through impacting nerve stem cell function or morphology. OBJECTIVE: To investigate the effects of isoflurane on the proliferation and differentiation of neural stem cells in the hippocampus of rats. METHODS: Neural stem cells from the hippocampus of neonatal Sprague-Dawley rats, aged 7 days, were induced and differentiated. Passage 3 cells were obtained and divided into two groups: isoflurane group (a mixture gas of 2.8% isoflurane, 5% CO2 and 95% O2) and control group (a mixture of 5% CO2 and 95% O2). After  intervention of 6 hours followed by 2 hours of routine culture, anti-BrdU monoclonal antibody immunofluorescent staining was used to detect cell proliferation, and western blot assay to detect the expression of β3-tubulin and glial fibrillary acidic protein. RESULTS AND CONCLUSION: Compared with the control group, the number of BrdU positive cells in the isoflurane group reduced significantly, indicating that isoflurane inhibits the proliferation of neural stem cells. Compared with the control group, the expression of glial fibrillary acidic protein in the isoflurane group up-regulated, but the expression of β3-tubulin had no changes, indicating isoflurane promotes the differentiation of neural stem cells into astrocytes.       

静压力对脂肪干细胞与静电纺丝纳米纤维细胞相容性的影响

BACKGROUND: Electrospun polylactic acid/polycaprolactone nanofibers (ENF) are a kind of self-synthesized biodegradable material. Our preliminary studies have indicated that the biomaterial exhibits excellent biocompatibility; however, the research about its mechanics is still little. OBJECTIVE: To explore the effects of static pressure on the cytocompatibility of adipose-derived stem cells on the ENF scaffold. METHODS: Adipose-derived stem cells were seeded onto the ENF scaffold, and then cultured in the low-glucose DMEM supplemented with 10% fetal bovine serum. The mixed constructs were submitted to the static pressure at 0, 15, 30, and 45 kPa for 4 hours using a static pressure device, respectively. Subsequently, the proliferation, adhesion and viability of adipose-derived stem cells on the ENF scaffold were detected using MTT assay and living/dead staining to evaluate the cytocompatibility. RESULTS AND CONCLUSION: MTT assay showed that there were significant differences in absorbance values among groups by one-way analysis of variance after 4 hours of loading with different static pressures in vitro. Under 0-30 kPa static pressure, the absorbance values increased with static pressure, but the absorbance values declined until the pressure reached 45 kPa, and multiple comparisons between groups showed significant difference. The significant differences in the cell attachment percentage by MTT assay could be found among groups. The living/dead staining results supported the above findings. Furthermore, the significant differences in percentage of living cells among groups were shown using either one-way analysis of variance or paired t test. In conclusion, the appropriate static pressure can promote the cytocompatibility, proliferation, adhesion and viability of adipose-derived stem cells on the ENF scaffold. But the excessive pressure is likely to inhibit the cellular biological behaviors, thus affecting cytocompatibility of adipose-derived stem cells with the ENF scaffold.     

The differentiation of embryonic stem cells seeded on electrospun nanofibers into neural lineages

Due to advances in stem cell biology, embryonic stem (ES) cells can be induced to differentiate into a particular mature cell lineage when cultured as embryoid bodies. Although transplantation of ES cells-derived neural progenitor cells has been demonstrated with some success for either spinal cord injury repair in small animal model, control of ES cell differentiation into complex, viable, higher ordered tissues is still challenging. Mouse ES cells have been induced to become neural progenitors by adding retinoic acid to embryoid body cultures for 4 days. In this study, we examine the use of electrospun biodegradable polymers as scaffolds not only for enhancing the differentiation of mouse ES cells into neural lineages but also for promoting and guiding the neurite outgrowth. A combination of electrospun fiber scaffolds and ES cells-derived neural progenitor cells could lead to the development of a better strategy for nerve injury repair.     

Gliotoxic effects of alpha-aminoadipic acid on monolayer cultures of dissociated postnatal mouse cerebellum

The cytotoxic effects of DL-, D- and L-alpha-aminoadipic acid, a six-carbon homologue of glutamate, were investigated in cell cultures of dissociated postnatal mouse cerebellum. Treatment with alpha-aminoadipic acid resulted in rapid nuclear and cytoplasmic swelling and, after longer periods of exposure, karyopyknosis of astrocytes, identified by indirect immunofluorescence labelling with anti-human glial fibrillary acidic protein antiserum. The number of astrocytes with pyknotic nuclei depended on the concentration of alpha-aminoadipic acid as well as on the duration of drug action. The presence of 0.21 mM DL-alpha-aminoadipic acid or 0.10 mM L-alpha-aminoadipic acid for 40 h caused karyopyknosis in 50% of the astrocytes. In contrast, D-alpha-aminoadipic acid, had little gliotoxic activity. None of the cytotoxic effects of DL-alpha-aminoadipic acid or L-alpha-aminoadipic acid observed for astrocytes were seen for the neurons present in the cultures when the drug was added after 4 days in vitro. Neurotoxic effects were evident, however, when alpha-aminoadipic acid was included in the culture medium at plating. These results indicate that alpha-adminoadpic acid can be used to substantially reduce the number of astroglia in cerebellar cultures and that dissociated cell cultures will provide a useful model with which to study the mechanisms of alpha-aminoadipic acid induced glial toxicity.