供体骨髓来源干细胞在骨髓嵌合小鼠肠上皮中定植和分化研究

目的 观察骨髓移植后供体骨髓来源干细胞（bone marrow derived stem cells，BMDSCs）是否能够在受体肠上皮中定植并分化为肠上皮细胞。方法 使用密度为1．073g／mL的Percoll分离GFP转基因小鼠的骨髓有核细胞。利用^60Co放射源对C57BL／6小鼠进行10Gy致死剂量照射，照射后4h经尾静脉移植绿色荧光蛋白（green fluorescence protein，GFP）转基因小鼠骨髓细胞建立嵌合小鼠模型，移植后1月和6月取小肠标本石蜡包埋。使用GFP抗体鉴定GFP阳性供体细胞在小肠上皮的表达情况，并使用GFP抗体和细胞角蛋白（PCK）抗体进行双标以判断BMDSCs是否分化上皮细胞，同时结合绒毛蛋白（Villin）和GFP的免疫荧光双标及连续切片染色肠道特异转录因子CDX2和GFP来分析骨髓来源细胞是否分化为肠道功能性上皮细胞。结果供体骨髓来源细胞在嵌合鼠的骨髓和小肠上皮层中均有定植，且小肠上皮中GFP阳性细胞能够同时表达PCK、Villin和CDX2。结论 供体骨髓来源干细胞可以在骨髓嵌合小鼠的肠上皮定植，并分化为具有正常功能的小肠上皮细胞。     

Assessment of cystic fibrosis transmembrane conductance regulator (CFTR) activity in CFTR-null mice after bone marrow transplantation

Several studies have demonstrated that bone marrow (BM)-derived cells give rise to rare epithelial cells in the gastrointestinal (GI) and respiratory tracts after BM transplantation into myeloablated recipients. We investigate whether, after transplantation of cystic fibrosis transmembrane conductance regulator (CFTR)-positive BM-derived cells, BM-derived GI and airway epithelial cells can provide CFTR activity in the GI tract and nasal epithelium of recipient cystic fibrosis mice. CFTR-/- mice were transplanted with wild-type BM after receiving different doses of irradiation, and CFTR activity was assessed in vivo in individual mice over time by using rectal and nasal potential difference analyses and in vitro by Ussing chamber analysis. The data suggest that rare BM-derived epithelial cells in the GI and nasal epithelium detected in CFTR-/- transplanted mice provide a modest level of CFTR-dependent chloride secretion. Detection of CFTR mRNA and protein in tissues of transplanted CFTR-/- mice supports these data.     

Adult stem cells from bone marrow stroma differentiate into airway epithelial cells: potential therapy for cystic fibrosis

Cystic fibrosis (CF), the most prevalent, fatal genetic disorder in the Caucasian population, is caused by mutations of CF transmembrane conductance regulator (CFTR). The mutations of this chloride channel alter the transport of chloride and associated liquid and thereby impair lung defenses. Patients typically succumb to chronic bacterial infections and respiratory failure. Restoration of the abnormal CFTR function to CF airway epithelium is considered the most direct way to treat the disease. In this report, we explore the potential of adult stem cells from bone marrow, referred to as mesenchymal or marrow stromal stem cells (MSCs), to provide a therapy for CF. We found that MSCs possess the capacity of differentiating into airway epithelia. MSCs from CF patients are amenable to CFTR gene correction, and expression of CFTR does not influence the pluripotency of MSCs. Moreover, the CFTR-corrected MSCs from CF patients are able to contribute to apical Cl(-) secretion in response to cAMP agonist stimulation, suggesting the possibility of developing cell-based therapy for CF. The ex vivo coculture system established in this report offers an invaluable approach for selection of stem-cell populations that may have greater potency in lung differentiation.     

Efficiency of bone marrow-derived cells in regeneration of the stomach after induction of ethanol-induced ulcers in rats

Background Bone marrow contains hematopoietic stem cells, nonhematopoietic mesenchymal stem cells, and several precursor cells for osteoblasts, chondrocytes, adipocytes, myocytes, hepatocytes, and even neural cells. Research findings indicate that multipotent stem cells in the adult body may be used to recover the lost functions of damaged tissues. This study examined the involvement of bone marrow-derived cells in the regeneration of the stomach after experimental gastric ulcers were produced in rats.Methods We transplanted the bone marrow of transgenic rats that expressed green fluorescence protein (GFP) throughout the body. Twenty-one days after the bone marrow transplantation (BMT), gastric ulceration was induced, using absolute ethanol. Control animals received saline. After various observation periods, rats harboring GFP-positive bone marrow-derived cells were killed, and the tissues were removed and processed to prepare paraffin-embedded sections. Cells expressing GFP were identified by conventional immunohistochemistry, using anti-GFP antibody. To identify whether cells expressing GFP were epithelial cells or interstitial cells such as fibroblasts, serial sections were examined with anti-cytokeratin antibody or anti-vimentin antibody, respectively. Furthermore, to confirm that cells expressing GFP were epithelial cells or interstitial cells, we used double-staining analysis with anti-GFP antibody or anti-cytokeratin antibody, respectively.Results GFP-positive, bone marrow-derived cells were found in the cytokeratin-positive gastrointestinal epithelium, as well as among vimentin-positive interstitial cells. Interestingly, the proportions of GFP-positive, cytokeratin-positive epithelial cells and vimentin-positive interstitial cells were significantly greater in the ethanol-treated damaged stomachs than in the saline-treated controls.Conclusions The present study clearly demonstrates that bone marrow-derived cells are involved in the regeneration of the stomach after ethanol-induced ulcers in rats.     

Chloride uptake into cultured airway epithelial cells from cystic fibrosis patients and normal individuals.

The chloride permeability of airway and sweat ductal epithelium of cystic fibrosis (CF) patients is decreased. This abnormality could represent an intrinsic characteristic of the epithelial cell or the response to a tonic extrinsic stimulus, in vivo. We cultured airway epithelial cells derived from CF and non-CF individuals under identical conditions that were free from donor-specific factors. Differences in the characteristics of cells that multiplied under these circumstances are unlikely to reflect the effects of extrinsic modulation present in the host. After 8-12 days in culture, the cells of CF and non-CF patients were similar in morphology and intracellular electrolyte content, but the CF cultures took up chloride at a reduced rate. The difference could not be attributed to a higher intracellular potential in CF cells or to the presence of a stilbene anion-sensitive chloride-chloride exchange in non-CF cells. We conclude that epithelial cells from CF patients grown in the absence of extracellular factors of the host express reduced cellular chloride permeability, a defect similar to that found in vivo and in freshly excised nasal epithelium.     

Epithelial cell-extracellular matrix interactions and stem cells in airway epithelial regeneration

In healthy subjects, the respiratory epithelium forms a continuous lining to the airways and to the environment, and plays a unique role as a barrier against external deleterious agents to protect the airways from the insults. In respiratory diseases such as cystic fibrosis (CF), chronic obstructive pulmonary disease (COPD), chronic bronchitis, or asthma, the airway epithelium is frequently remodeled and injured, leading to the impairment of its defense functions. The rapid restoration of the epithelial barrier is crucial for these patients. The complete regeneration of the airway epithelium is a complex phenomenon, including not only the epithelial wound repair but also the epithelial differentiation to reconstitute a fully well differentiated and functional epithelium. The regeneration implies two partners: the epithelial stem/progenitor cells and factors able to regulate this process. Among these factors, epithelial cells-extracellular matrix (ECM) interactions play a crucial role. The secretion of a provisional ECM, the cell-ECM relationships through epithelial receptors, and the remodeling of the ECM by proteases (mainly matrix metalloproteinases) contribute not only to airway epithelial repair by modulating epithelial cell migration and proliferation, but also to the differentiation of repairing cells leading to the complete restoration of the wounded epithelium. A better characterization of resident stem cells and of effectors of the regeneration process is an essential prerequisite to propose new regenerative therapeutics to patients suffering from infectious/inflammatory respiratory diseases.     

骨髓细胞参与甘油引起的小鼠急性肾小管坏死修复的实验观察

目的：观察骨髓来源的细胞能否分化成肾小管上皮细胞。方法：15只绿色荧光蛋白（GFP）标记的C57BL／6转基因小鼠提供骨髓细胞，64只同种无荧光标记的C57BL／6小鼠随机分为正常对照组（N组）、全身照射组（TBI组）、骨髓移植组（BMT组）、骨髓移植＋甘油注射组（B＋G组），每组16只。各组小鼠于不同时间点取血检测血常规、尿素氮及血肌酐，并取肾行H-E染色检查肾脏病理变化。流式细胞仪可以明确受体鼠骨髓细胞中CFP阳性细胞的比例，利用荧光显微镜及激光共聚焦显微镜采用荧光组织化学、免疫组织化学等方法观察GFP阳性细胞在受体鼠肾脏的分布及数量。结果：致死剂量^60Co照射虽然引起血常规三系减少，但并未对肾脏的组织结构及功能造成损伤。BMT组受体鼠在骨髓移植后第56天、84天时，肾小管中有少量GFP阳性细胞的存在，B＋G组受体鼠于上述同样时间点时肾小管中的GFP阳性细胞增多。激光共聚焦显微镜进一步证实了这些GFP阳性细胞位于肾小管上皮，并且荧光组织化学显示，这些GFP阳性细胞表达肾小管上皮细胞特异性功能蛋白Megalin。结论：骨髓细胞可以向肾小管上皮细胞分化．参与肾小管上皮细胞的更新。并且损伤可以使骨髓细胞的肾向分化率增加。     

急性肺损伤干细胞修复的研究进展

急性肺损伤/急性呼吸窘迫综合征的重要病理改变是肺泡上皮损伤,进而引起肺泡-毛细血管膜的损伤,出现气体弥散障碍。肺内自身存在及肺外组织来源的干细胞在肺损伤时可分化为上皮细胞,修复损伤肺组织的结构和功能,发挥治疗作用。本文就近年来国外对这方面的研究作一综述。     

Mesenchymal stem cells obtained after bone marrow transplantation or peripheral blood stem cell transplantation originate from host tissue

Mesenchymal stem cells (MSC) obtained from human bone marrow have been described as adult stem cells with the ability of extensive self-renewal and clonal expansion, as well as the capacity to differentiate into various tissue types and to modulate the immune system. Some data indicate that leukapheresis products may also contain non-hematopoietic stem cells, as they occur in whole bone marrow transplantation (BMT). However, there is still controversy whether MSC expand in the host after transplantation like blood progenitor cells do. Therefore, we were interested in finding out if graft MSC can be detected in leukapheresis products and in bone marrow after BMT and peripheral blood stem cell transplantation (PBSCT). Every sample from total bone marrow transplants exhibited growth of MSC after in vitro culture, but not one of nine leukapheresis products did. In addition, bone marrow aspirates of 9 patients receiving BMT and of 18 patients after PBSCT were examined for origin of MSC. Almost all MSC samples exhibited a complete host profile, whereas peripheral blood cells were of donor origin. We conclude that even if trace amounts of MSC are co-transplanted during PBSCT or BMT, they do not expand significantly in the host bone marrow.     

Alternative sources of hepatocytes for cell therapy

There is an urgent need to search for alternatives to whole organ transplantation. Several methods have been proposed. Among these strategies, cell transplantation is currently one of the most promising. To achieve this aim, in addition to highly differentiated adult hepatocytes, the use of stem cells is considered a highly attractive therapeutic method for the treatment of liver disease and for temporary support of hepatic function until a liver becomes available for organ transplantation. This strategy is based on the ability of stem cells to differentiate into different cellular types according to their environment. Therefore, stem cells could be an unlimited source of hepatic cells for transplantation and gene therapy. Bone marrow is considered the most promising source of adult stem cells, partly due to the versatility of the cells obtained in repairing damaged tissues of several lineages. Several different types of stem cells have been described in bone marrow: hematopoietic, mesenchymal, side population and multipotent adult stem cells. Bone marrow cells have been hypothesized as a third recruitment source in liver regeneration in addition to hepatocytes and endogenous liver stem cells. Consequently, attempts have been made to differentiate them into hepatic lineage for their subsequent use in hepatic cell therapy. The present article reviews the progress made in this field or research.     

骨髓基质干细胞向心肌细胞分化的研究进展

骨髓基质干细胞不仅有一定的自我更新能力,可以分化为骨、软骨和脂肪等多种类型的基质细胞,在一定外界环境条件下还能实现跨系统分化,分化成心肌细胞,是目前认为较有希望成为心肌梗死替代治疗的干细胞。现就骨髓基质干细胞的生物学特性、向心肌细胞分化的诱导因素及临床应用进展进行综述。     

Plasticity of marrow-derived stem cells

Bone marrow (BM) contains hematopoietic stem cells (HSCs), which differentiate into every type of mature blood cell; endothelial cell progenitors; and marrow stromal cells, also called mesenchymal stem cells (MSCs), which can differentiate into mature cells of multiple mesenchymal tissues including fat, bone, and cartilage. Recent findings indicate that adult BM also contains cells that can differentiate into additional mature, nonhematopoietic cells of multiple tissues including epithelial cells of the liver, kidney, lung, skin, gastrointestinal (GI) tract, and myocytes of heart and skeletal muscle. Experimental results obtained in vitro and in vivo are the subject of this review. The emphasis is on how these experiments were performed and under what conditions differentiation from bone marrow to epithelial and neural cells occurs. Questions arise regarding whether tissue injury is necessary for this differentiation and the mechanisms by which it occurs. We also consider which bone marrow subpopulations are capable of this differentiation. Only after we have a better understanding of the mechanisms involved and of the cells required for this differentiation will we be able to fully harness adult stem cell plasticity for clinical purposes.     

Therapeutic effect of transplanting HGF-treated bone marrow mesenchymal cells into CCl4-injured rats

BACKGROUND/AIMS: The autologous transplantation of bone marrow cells is a promising treatment for liver disease. Pluripotent bone marrow stem cells can differentiate into hepatocytes, but few reports address the therapeutic effect of transplanting these stem cells into damaged liver in vivo. Here, we transplanted bone marrow-derived mesenchymal cells (BMMCs) to test their effect in liver-injured rats. METHODS: Rat bone marrow cells were cultivated for 2 weeks in the presence or absence of hepatocyte growth factor (HGF), labeled with a fluorescent marker, and transplanted by injection into CCl(4)-injured rats. Blood samples collected 4 weeks later were analyzed for albumin production and transaminase levels. The amount of fibrosis was determined by histology. RESULTS: RT-PCR analysis detected alpha-fetoprotein and albumin mRNAs in BMMCs cultured with HGF for 2 weeks. Albumin protein was also produced in the BMMC cultures by a subpopulation of cells. Transplantation of the BMMCs into liver-injured rats restored their serum albumin level and significantly suppressed transaminase activity and liver fibrosis. These effects were not seen when the BMMCs were cultured without HGF. CONCLUSIONS: The transplantation of BMMCs cultured with HGF effectively treats liver injury in rats. This is a promising technique for autologous transplantation in humans with liver injury.     

Little evidence of transdifferentiation of bone marrow-derived cells into pancreatic beta cells

Aims/hypothesis Bone marrow cells contain at least two distinct types of stem cells which are haematopoietic stem cells and mesenchymal stem cells. Both cells have the ability to differentiate into a variety of cell types derived from all three germ layers. Thus, bone marrow stem cells could possibly be used to generate new pancreatic beta cells for the treatment of diabetes. In this study, we investigated the feasibility of bone marrow-derived cells to differentiate into beta cells in pancreas.Methods Using green fluorescent protein transgenic mice as donors, the distribution of haematogenous cells in the pancreas was studied after bone marrow transplantation.Results In the pancreas of green fluorescent protein chimeric mice, green fluorescent protein-positive cells were found in the islets, but none of these cells expressed insulin. Previous data has suggested that tissue injury can recruit haematopoietic stem cells or their progeny to a non-haematopietic cell fate. Therefore, low-dose streptozotocin (30 or 50 mg/kg on five consecutive days) was injected into the mice 5 weeks after bone marrow transplantation, but no green fluorescent protein-positive cells expressing insulin were seen in the islets or around the ducts of the pancreas.Conclusions/interpretation Our data suggests that bone marrow-derived cells are a distinct cell population from islet cells and that transdifferentiation from bone marrow-derived cells to pancreatic beta cells is rarely observed.Abbreviations STZ streptozotocin - EGFP enhanced green fluorescent protein - GP guinea-pig - vWF von Willebrand Factor - BrdU bromodeoxyuridine - GFP green fluorescent protein - IPGTT Intraperitoneal glucose tolerance test     

Molecular and clinical basis for the regeneration of human gastrointestinal epithelia

In the gastrointestinal tract, rapid renewal of the epithelium continues throughout life. Therefore, it is believed that the gastrointestinal epithelium has a prominent capacity for regeneration when tissue damage occurs. However, we face some clinical conditions in which regeneration of the gastrointestinal epithelia is severely disturbed. One example is the refractory ulcers seen in the intestine of inflammatory bowel disease patients, and a novel therapy to regenerate damaged intestinal epithelia is earnestly desired in those conditions. Little is known about the maintenance and regeneration of the intestinal epithelia, and a molecular or clinical basis for regenerative medicine is totally lacking at the moment. In this review, we discuss recent findings of the molecules regulating the proliferation and differentiation of epithelial cells. Further study of these molecules may lead to the identification and purification of intestinal stem cells that may be used as a source for transplantation in diseased patients. Endogenous stem cells also could be manipulated to correct dysregulated or prolonged regeneration in diseased patients. Alternatively, we will raise bone marrow cells as another novel source for regenerating the intestinal epithelia. Bone marrow-derived cells are the only cells of extragastrointestinal origin that are shown to contribute to the regeneration of the gastrointestinal epithelia. In bone marrow transplant recipients, donor-derived epithelial cells substantially repopulated the gastrointestinal tract during epithelial regeneration after graft-versus-host disease or ulcer formation. Utilization of these cells may also lead to a novel therapy to regenerate the damaged gastrointestinal epithelia, whether by bone marrow transplantation or by the administration of humoral factors.     

Isolation of multipotent mesenchymal stem cells from umbilical cord blood

It is well accepted that umbilical cord blood has been a source for hematopoietic stem cells. However, controversy exists as to whether cord blood can serve as a source of mesenchymal stem cells, which can differentiate into cells of different connective tissue lineages such as bone, cartilage, and fat, and little success has been reported in the literature about the isolation of such cells from cord blood. Here we report a novel method to obtain single cell-derived, clonally expanded mesenchymal stem cells that are of multilineage differentiation potential by negative immunoselection and limiting dilution. The immunophenotype of these clonally expanded cells is consistent with that reported for bone marrow mesenchymal stem cells. Under appropriate induction conditions, these cells can differentiate into bone, cartilage, and fat. Surprisingly, these cells were also able to differentiate into neuroglial- and hepatocyte-like cells under appropriate induction conditions and, thus, these cells may be more than mesenchymal stem cells as evidenced by their ability to differentiate into cell types of all 3 germ layers. In conclusion, umbilical cord blood does contain mesenchymal stem cells and should not be regarded as medical waste. It can serve as an alternative source of mesenchymal stem cells to bone marrow.     

Mesenchymal stem cells: heading into the clinic

In recent years, there has been an increasing interest in non-hematopoietic pluripotent progenitor cells that are found in the bone marrow. Mesenchymal stem cells (MSCs) are the first non-hematopoietic progenitors to be isolated from the bone marrow and extensively characterized. In addition to their ability to support hematopoiesis, MSCs can differentiate into osteocytes, chondrocytes, tenocytes, adipocytes and smooth muscle cells. This article will review our current understanding of bone marrow stroma and MSCs and their potential therapeutic role in the setting of hematopoietic stem cell transplantation.     

Mesenchymal stem cells remain of host origin even a long time after allogeneic peripheral blood stem cell or bone marrow transplantation

OBJECTIVE: Plasticity of hematopoietic stem cells (HSC) has gained major interest in stem cell research. In order to investigate whether HSC may differentiate into mesenchymal stem cells (MSC), we assessed chimerism in peripheral blood (PB), mononuclear cell fractions (MNC) of bone marrow, and MSC derived from bone marrow (BM) from 27 up to 4225 days after allogeneic transplantation. PATIENTS AND METHODS: We applied fluorescence in situ hybridization using X/Y gene probes in sex-mismatched and STR-PCR in sex-matched patients. MSC could have been generated in 27 of 55 bone marrow samples derived from 20 patients. Fifteen patients received peripheral blood stem cell transplants (PBSCT), including CD34-selected PBSCT in two. Five patients received bone marrow. RESULTS: While all patients had chimerism in PB and MNC of the BM, in all but one patient BM-derived MSC were of recipient origin. This single patient showed reproducibly MSC of donor origin in a frequency of 1% after having received a CD34-selected PBSCT. Looking at graft collections, MSCs were easily generated from BM specimens, while no MSC could be derived from PBSC samples. CONCLUSION: Even though HSC have been found to differentiate into a variety of nonhematological cell types, they usually do not differentiate into MSC after allogeneic transplantation.