Differential bone‐forming capacity of osteogenic cells from either embryonic stem cells or bone marrow‐derived mesenchymal stem cells

For more than a decade, human mesenchymal stem cells (hMSCs) have been used in bone tissue‐engineering research. More recently some of the focus in this field has shifted towards the use of embryonic stem cells. While it is well known that hMSCs are able to form bone when implanted subcutaneously in immune‐deficient mice, the osteogenic potential of embryonic stem cells has been mainly assessed in vitro. Therefore, we performed a series of studies to compare the in vitro and in vivo osteogenic capacities of human and mouse embryonic stem cells to those of hMSCs. Embryonic and mesenchymal stem cells showed all characteristic signs of osteogenic differentiation in vitro when cultured in osteogenic medium, including the deposition of a mineralized matrix and expression of genes involved in osteogenic differentiation. As such, based on the in vitro results, osteogenic ES cells could not be discriminated from osteogenic hMSCs. Nevertheless, although osteogenic hMSCs formed bone upon implantation, osteogenic cells derived from both human and mouse embryonic stem cells did not form functional bone, indicated by absence of osteocytes, bone marrow and lamellar bone. Although embryonic stem cells show all signs of osteogenic differentiation in vitro, it appears that, in contrast to mesenchymal stem cells, they do not possess the ability to form bone in vivo when a similar culture method and osteogenic differentiation protocol was applied. Copyright © 2010 John Wiley & Sons, Ltd.     

骨髓间充质干细胞旁分泌对急性心肌梗死心肌的保护作用

背景：成人心肌细胞缺乏再生能力,使用细胞疗法再生和修复心肌,可能提高心肌缺血性损伤后功能。目的：探索骨髓间充质干细胞治疗急性心肌梗死中可能的作用机制。方法：密度梯度离心法从SD大鼠中分离培养骨髓间充质干细胞。20只大鼠以开胸冠状动脉结扎法制备急性心肌梗死模型后,随机等分为模型组和骨髓间充质干细胞组,骨髓间充质干细胞组大鼠于冠状动脉结扎后通过尾静脉注射骨髓间充质干细胞。结果与结论：造模6个月后,与模型组相比,骨髓间充质干细胞组大鼠心脏功能明显改善,心肌组织血管密度增加,细胞凋亡数量减少,心脏组织中炎症因子血管内皮生长因子、von Willebrand因子、肿瘤生长因子3β和白细胞介素1βmRNA表达明显增加。提示骨髓间充质干细胞通过调节心脏炎症因子与血管因子的分泌起到保护急性心肌梗死后心肌细胞的作用。     

Temporal profiling of the growth and multi‐lineage potentiality of adipose tissue‐derived mesenchymal stem cells cell‐sheets

Cell‐sheet tissue engineering retains the benefits of an intact extracellular matrix (ECM) and can be used to produce scaffold‐free constructs. Adipose tissue‐derived stem cells (ASCs) are multipotent and more easily obtainable than the commonly used bone marrow‐derived stem cells (BMSCs). Although BMSC cell sheets have been previously reported to display multipotentiality, a detailed study of the development and multilineage potential of ASC cell sheets (ASC‐CSs) is non‐existent in the literature. The aims of this study were to temporally profile: (a) the effect of hyperconfluent culture duration on ASC‐CSs development; and (b) the multipotentiality of ASC‐CSs by differentiation into the osteogenic, adipogenic and chondrogenic lineages. Rabbit ASCs were first isolated and cultured until confluence (day 0). The confluent cells were then cultured in ascorbic acid‐supplemented medium for 3 weeks to study cell metabolic activity, cell sheet thickness and early differentiation gene expressions at weekly time points. ASC‐CSs and ASCs were then differentiated into the three lineages, using established protocols, and assessed by RT–PCR and histology at multiple time points. ASC‐CSs remained healthy up to 3 weeks of hyperconfluent culture. One week‐old cell sheets displayed upregulation of early differentiation gene markers (Runx2 and Sox9); however, subsequent differentiation results indicated that they did not necessarily translate to an improved phenotype. ASCs within the preformed cell sheet groups did not differentiate as efficiently as the non‐hyperconfluent ASCs, which were directly differentiated. Although ASCs within the cell sheets retained their differentiation capacity and remained viable under prolonged hyperconfluent conditions, future applications of ASC‐CSs in tissue engineering should be considered with care. Copyright © 2016 John Wiley & Sons, Ltd.     

MRI活体示踪心肌梗死大鼠骨髓间充质干细胞的移植

背景：干细胞移植的疗效和安全性评估均需要对体内干细胞的存活、分布、迁徙、增殖及分化进行连续监测。目的：观察MRI示踪超顺磁性氧化铁标记的骨髓间充质干细胞在缺血心肌组织的分布、迁徙情况。方法：直接贴壁法分离和培养大鼠骨髓间充质干细胞,获得的细胞进行免疫鉴定。以新型超顺磁性氧化铁标记骨髓间充质干细胞,体外MRI成像确定其体内示踪的可行性。标记后锥虫蓝拒染试验、MTT比色试验分别检测标记细胞的活力、增殖情况。60只SD大鼠随机分为3组,制备大鼠心肌梗死模型2周后再次开胸移植含标记骨髓间充质干细胞的PBS混合液、含未标记骨髓间充质干细胞的PBS混合液和等量PBS。于移植后第1天、第3周行MRI检查,动态观察移植细胞的分布、迁徙,并根据MRI图像定位选择性行CD90免疫组化检查。结果与结论：骨髓间充质于细胞标记后,普鲁士蓝染色见胞浆内蓝色铁颗粒,标记效率为99％,标记细胞与未标记细胞间锥虫蓝拒染率、MTT吸光度差异无显著性意义。体外MRI可检测到标记细胞,并在T2WI及T2W／FFE序列上呈低信号。细胞移植1d后,在T2WI及T2W／FFE序列上可见标记细胞在梗死心肌边缘呈类圆形低信号;移植3周后,移植区域信号边界模糊,范围扩大,对比度降低。CD90免疫组化检测证实移植细胞可由梗死边缘向梗死区域迁徙。结果可见新型超顺磁性氧化铁可成功对大鼠骨髓间充质干细胞进行标记,细胞标记后可被MRI检测。     

门控心肌灌注显像评价高海拔地区骨髓干细胞移植治疗心肌梗死的疗效

目的 用99Tcm-MIBI门控心肌灌注显像评价经冠状动脉内自体骨髓干细胞移植后高海拔地区急性心肌梗死后心功能及心肌灌注的变化.方法 33例前壁心肌梗死患者随机分为两组.18例(对照组)仅行经皮冠状动脉腔内成形术,余14例(移植组)在此基础上行干细胞移植术.均于术前及术后6和12个月行静息心肌灌注显像.结果 干细胞移植术后6个月,移植组患者的左心室射血分数(LVEF)较术前提高8%～9%,而对照组患者术后6个月随访LVEF改善程度均低于移植组.结论 骨髓干细胞移植可明显改善心肌收缩功能和心肌灌注.     

A composite Gelatin/hyaluronic acid hydrogel as an ECM mimic for developing mesenchymal stem cell‐derived epithelial tissue patches

Here we report fabrication of Gelatin‐based biocomposite films and their application in developing epithelial patches. The films were loaded with an epithelial cell growth factor cocktail and used as an extracellular matrix mimic for in vitro regeneration of organized respiratory epithelium using Calu‐3 cell line and mesenchymal stem cells (MSCs). Our data show differentiation of Calu‐3 cells on composite films as evidenced by tight junction protein expression and barrier formation. The films also supported attachment, migration, and proliferation of alveolar basal epithelial cell line A549. We also show the suitability of the composite films as a biomimetic scaffold and growth factor delivery platform for differentiation of human MSCs to epithelial cells. MSCs differentiation to the epithelial lineage was confirmed by staining for epithelial and stem cell specific markers. Our data show that the MSCs acquire the epithelial characteristics after 2 weeks with significant reduction in vimentin, increase in pan cytokeratin expression, and morphological changes. However, despite the expression of epithelial lineage markers, these cells did not form fully functional tight junctions as evidenced by low expression of junctional protein ZO1. Further optimisation of culture conditions and growth factor cocktail is required to enhance tight junction formation in MSCs‐derived epithelial cells on the composite hydrogels. Nevertheless, our data clearly highlight the possibility of using MSCs in epithelial tissue engineering and the applicability of the composite hydrogels as transferrable extracellular matrix mimics and delivery platforms with potential applications in regenerative medicine and in vitro modelling of barrier tissues.     

Adipose‐ and bone marrow‐derived mesenchymal stem cells display different osteogenic differentiation patterns in 3D bioactive glass‐based scaffolds

Mesenchymal stem cells can be isolated from a variety of different sources, each having their own peculiar merits and drawbacks. Although a number of studies have been conducted comparing these stem cells for their osteo‐differentiation ability, these are mostly done in culture plastics. We have selected stem cells from either adipose tissue (ADSCs) or bone marrow (BMSCs) and studied their differentiation ability in highly porous three‐dimensional (3D) 45S5 Bioglass®‐based scaffolds. Equal numbers of cells were seeded onto 5 × 5 × 4 mm³ scaffolds and cultured in vitro, with or without osteo‐induction medium. After 2 and 4 weeks, the cell–scaffold constructs were analysed for cell number, cell spreading, viability, alkaline phosphatase activity and osteogenic gene expression. The scaffolds with ADSCs displayed osteo‐differentiation even without osteo‐induction medium; however, with osteo‐induction medium osteogenic differentiation was further increased. In contrast, the scaffolds with BMSCs showed no osteo‐differentiation without osteo‐induction medium; after application of osteo‐induction medium, osteo‐differentiation was confirmed, although lower than in scaffolds with ADSCs. In general, stem cells in 3D bioactive glass scaffolds differentiated better than cells in culture plastics with respect to their ALP content and osteogenic gene expression. In summary, 45S5 Bioglass‐based scaffolds seeded with ADSCs are well‐suited for possible bone tissue‐engineering applications. Induction of osteogenic differentiation appears unnecessary prior to implantation in this specific setting. Copyright © 2013 John Wiley & Sons, Ltd.     

Modulation of human mesenchymal stem cell function in a three‐dimensional matrix promotes attenuation of adverse remodelling after myocardial infarction

The application of tissue engineering (TE) practices for cell delivery offers a unique approach to cellular cardiomyoplasty. We hypothesized that human mesenchymal stem cells (hMSCs) applied to the heart in a collagen matrix would outperform the same cells grown in a monolayer and directly injected for cardiac cell replacement after myocardial infarction in a rat model. When hMSC patches were transplanted to infarcted hearts, several measures for left ventricle (LV) remodelling and function were improved, including fractional area change, wall thickness, –dP/dt and LV end‐diastolic pressure. Neovessel formation throughout the LV infarct wall after hMSC patch treatment increased by 37% when compared to direct injection of hMSCs. This observation was correlated with increased secretion of angiogenic factors, with accompanying evidence that these factors enhanced vessel formation (30% increase) and endothelial cell growth (48% increase) in vitro. These observations may explain the in vivo observations of increased vessel formation and improved cardiac function with patch‐mediated cell delivery. Although culture of hMSC in collagen patches enhanced angiogenic responses, there was no effect on cell potency or viability. Therefore, hMSCs delivered as a cardiac patch showed benefits above those derived from monolayers and directly injected. hMSCs cultured and delivered within TE constructs may represent a good option to maximize the effects of cellular cardiomyoplasty. Copyright © 2011 John Wiley & Sons, Ltd.     

Cardiac regeneration using human‐induced pluripotent stem cell‐derived biomaterial‐free 3D‐bioprinted cardiac patch in vivo

One of the leading causes of death worldwide is heart failure. Despite advances in the treatment and prevention of heart failure, the number of affected patients continues to increase. We have recently developed 3D‐bioprinted biomaterial‐free cardiac tissue that has the potential to improve cardiac function. This study aims to evaluate the in vivo regenerative potential of these 3D‐bioprinted cardiac patches. The cardiac patches were generated using 3D‐bioprinting technology in conjunction with cellular spheroids created from a coculture of human‐induced pluripotent stem cell‐derived cardiomyocytes, fibroblasts, and endothelial cells. Once printed and cultured, the cardiac patches were implanted into a rat myocardial infarction model (n = 6). A control group (n = 6) without the implantation of cardiac tissue patches was used for comparison. The potential for regeneration was measured 4 weeks after the surgery with histology and echocardiography. 4 weeks after surgery, the survival rates were 100% and 83% in the experimental and the control group, respectively. In the cardiac patch group, the average vessel counts within the infarcted area were higher than those within the control group. The scar area in the cardiac patch group was significantly smaller than that in the control group. (Figure S1 ) Echocardiography showed a trend of improvement of cardiac function for the experimental group, and this trend correlated with increased patch production of extracellular vesicles. 3D‐bioprinted cardiac patches have the potential to improve the regeneration of cardiac tissue and promote angiogenesis in the infarcted tissues and reduce the scar tissue formation.     

Glial cell‐derived neurotrophic factor promotes dental pulp stem cell migration

Preserving the vitality of the teeth is critical in maintaining the function and aesthetics of teeth during dental treatment. Dental pulp stem cells (DPSCs) are mesenchymal cells that are demonstrated to possess stem cell properties, such as self‐renewal, proliferation, and pluripotency. DPSCs can be obtained through non‐invasive procedure from the dental pulp and become potential resources for tissue regeneration. Neurotrophic factors are known to promote survival and growth of neurons. In the present study, we examined the expression of the glial cell‐derived neurotrophic factor (GDNF) family ligands and receptors and characterized the intracellular localization of them in DPSCs. GDNF increased the migration of the DPSCs. In addition, we found that the AKT and MAPK pathways were downstream of GDNF in regulating the DPSC wound healing and migration. Our results indicate that neurotrophic factors play a role in dental pulp regeneration and may be potential novel therapies for post pulpotomy treatment in adult teeth.     

骨髓间充质干细胞移植心肌梗死大鼠的心功能

背景：前期研究发现移植的骨髓间充质干细胞能在受损心肌组织内存活和分化。目的：进一步观察局部注射移植同种异体骨髓间充质干细胞对心肌梗死模型大鼠心功能的影响。方法：体外培养的同种异体骨髓间充质干细胞达到一定数量（106）后用BrdU标记。24只SD大鼠随机分为3组：正常对照组未行冠状动脉前降支结扎,取骨髓间充质干细胞约1mL直接注射到冠状动脉前降支心肌的周围;假移植组：在冠状动脉前降支结扎后7d,取等量DMEM培养液直接注射到梗死心肌的周围;骨髓间充质干细胞移植组：冠状动脉前降支结扎后7d,取等量骨髓间充质干细胞直接注射到梗死心肌的周围;分别于移植前、移植后5周测定大鼠心功能。结果与结论：①移植后5周假移植组最大左室收缩末压、左室内压最大（最小）变化速率均低于移植前（P〈0.01）,而左室舒张末压高于移植前（P〈0.01）;移植后5周骨髓间充质干细胞移植组最大左室收缩末压、左室内压最大（最小）变化速率高于移植前（P〈0.01）,而左室舒张末压低于移植前（P〈0.01）。②移植后5周,骨髓间充质干细胞移植组大鼠的最大左室收缩末压、左室内压最大（最小）变化速率均高于假移植组（P〈0.01）,而左室舒张末压明显低于假移植组（P〈0.01）。结果可见骨髓间充质干细胞移植可明显改善心肌梗死模型大鼠心功能。     

The effect of serum on the proliferation of bone marrow‐derived mesenchymal stem cells from aged donors and donors with or without chronic heart failure

Many clinical studies of regenerative medicine using bone marrow‐derived mesenchymal stem cells (MSCs) have been conducted globally. We initiated clinical studies using MSCs in 2001 and have now treated over 100 cases with patients aged 0–92 years. In a few cases involving patients with chronic heart failure (CHF), we observed that MSCs proliferated poorly. This contrasts with cell therapy studies wherein MSCs of patients with CHF were used for treatment. The effects of serum on the proliferation of MSCs from donors with normal heart function and with CHF have not been reported. Moreover, whether cell therapy is effective for elderly patients remains uncertain. Therefore, characterization of MSCs from aged donors and/or donors with CHF is urgently required. We retrospectively analysed the population doubling times (PDTs) of MSCs between the first and second passages. Although we had data for many samples of well‐expanded MSCs from aged donors, a positive correlation was observed between donor age and PDT. A trend towards reduced variance in PDTs was observed in MSCs supplemented with fetal bovine serum (FBS) compared with those supplemented with autologous serum. When autologous serum was used, the average PDT of MSCs from donors with CHF was significantly longer than that of MSCs from donors without CHF. In contrast, when FBS was used, similar PDTs were observed in MSCs from donors with and without CHF. Thus, FBS promotes MSC expansion even from donors with CHF and MSC‐based regenerative medicine might be feasible even for elderly patients. Copyright © 2016 John Wiley & Sons, Ltd.     

Improved expansion of human bone marrow‐derived mesenchymal stem cells in microcarrier‐based suspension culture

Human bone marrow‐derived mesenchymal stem cells (hBM‐MSCs) have potential clinical utility in the treatment of a multitude of ailments and diseases, due to their relative ease of isolation from patients and their capacity to form many cell types. However, hBM‐MSCs are sparse, and can only be isolated in very small quantities, thereby hindering the development of clinical therapies. The use of microcarrier‐based stirred suspension bioreactors to expand stem cell populations offers an approach to overcome this problem. Starting with standard culture protocols commonly reported in the literature, we have successfully developed new protocols that allow for improved expansion of hBM‐MSCs in stirred suspension bioreactors using CultiSpher‐S microcarriers. Cell attachment was facilitated by using intermittent bioreactor agitation, removing fetal bovine serum, modifying the stirring speed and manipulating the medium pH. By manipulating these parameters, we enhanced the cell attachment efficiency in the first 8 h post‐inoculation from 18% (standard protocol) to 72% (improved protocol). Following microcarrier attachment, agitation rate was found to impact cell growth kinetics, whereas feeding had no significant effect. By serially subculturing hBM‐MSCs using the new suspension bioreactor protocols, we managed to obtain cell fold increases of 10³ within 30 days, which was superior to the 200‐fold increase obtained using the standard protocol. The cells were found to retain their defining characteristics after several passages in suspension. This new bioprocess represents a more efficient approach for generating large numbers of hBM‐MSCs in culture, which in turn should facilitate the development of new stem cell‐based therapies. Copyright © 2012 John Wiley & Sons, Ltd.     

Development of decellularized scaffolds for stem cell‐driven tissue engineering

Organ transplantation is an effective treatment for chronic organ dysfunctioning conditions. However, a dearth of available donor organs for transplantation leads to the death of numerous patients waiting for a suitable organ donor. The potential of decellularized scaffolds, derived from native tissues or organs in the form of scaffolds has been evolved as a promising approach in tissue‐regenerative medicine for translating functional organ replacements. In recent years, donor organs, such as heart, liver, lung and kidneys, have been reported to provide acellular extracellular matrix (ECM)‐based scaffolds through the process called ‘decellularization’ and proved to show the potential of recellularization with selected cell populations, particularly with stem cells. In fact, decellularized stem cell matrix (DSCM) has also emerged as a potent biological scaffold for controlling stem cell fate and function during tissue organization. Despite the proven potential of decellularized scaffolds in tissue engineering, the molecular mechanism responsible for stem cell interactions with decellularized scaffolds is still unclear. Stem cells interact with, and respond to, various signals/cues emanating from their ECM. The ability to harness the regenerative potential of stem cells via decellularized ECM‐based scaffolds has promising implications for tissue‐regenerative medicine. Keeping these points in view, this article reviews the current status of decellularized scaffolds for stem cells, with particular focus on: (a) concept and various methods of decellularization; (b) interaction of stem cells with decellularized scaffolds; (c) current recellularization strategies, with associated challenges; and (iv) applications of the decellularized scaffolds in stem cell‐driven tissue engineering and regenerative medicine. Copyright © 2015 John Wiley & Sons, Ltd.     

In vivo cartilage repair using adipose‐derived stem cell‐loaded decellularized cartilage ECM scaffolds

We have previously reported a natural, human cartilage ECM (extracellular matrix)‐derived three‐dimensional (3D) porous acellular scaffold for in vivo cartilage tissue engineering in nude mice. However, the in vivo repair effects of this scaffold are still unknown. The aim of this study was to further explore the feasibility of application of cell‐loaded scaffolds, using autologous adipose‐derived stem cells (ADSCs), for cartilage defect repair in rabbits. A defect 4 mm in diameter was created on the patellar groove of the femur in both knees, and was repaired with the chondrogenically induced ADSC–scaffold constructs (group A) or the scaffold alone (group B); defects without treatment were used as controls (group C). The results showed that in group A all defects were fully filled with repair tissue and at 6 months post‐surgery most of the repair site was filled with hyaline cartilage. In contrast, in group B all defects were partially filled with repair tissue, but only half of the repair tissue was hyaline cartilage. Defects were only filled with fibrotic tissue in group C. Indeed, histological grading score analysis revealed that an average score in group A was higher than in groups B and C. GAG and type II collagen content and biomechanical property detection showed that the group A levels approached those of normal cartilage. In conclusion, ADSC‐loaded cartilage ECM scaffolds induced cartilage repair tissue comparable to native cartilage in terms of mechanical properties and biochemical components. Copyright © 2012 John Wiley & Sons, Ltd.     

Donor‐matched comparison of dental pulp stem cells and bone marrow‐derived mesenchymal stem cells in a rat model

Dental pulp stem cells (DPSCs) have drawn much interest for the regeneration of mineralized tissues, and several studies have compared DPSCs to bone marrow‐derived mesenchymal stem cells (BMMSCs). However, conflicting results, possibly due to donor‐associated variability, have been published and the regenerative potential of DPSCs is currently unclear. In the present study we have sought to address this problem using a donor‐matched experimental design to robustly compare the biological properties of DPSCs and BMMSCs. All experiments were performed using cells isolated from a single adult Sprague–Dawley rat. Our results show that DPSCs and BMMSCs had similar morphologies and flow cytometry profiles, were capable of forming colonies in vitro and were capable of osteogenic, chondrogenic and adipogenic differentiation. However, quantitative comparisons revealed that DPSCs had a faster population doubling time and a higher percentage of stem/progenitor cells in the population, as determined by clonogenic assays. Furthermore, while both cell populations formed mineral in vitro, DPSCs had significantly higher alkaline phosphatase activity than BMMSCs after 3 weeks in osteogenic medium. These data show several key differences between DPSCs and BMMSCs and support the possibility of using DPSCs for mineralized tissue regeneration. Copyright © 2009 John Wiley & Sons, Ltd.