调控细胞迁移和组织再生的生物材料研究

组织再生材料为细胞、组织的生长提供必要的物质基础,维持再生组织的形状和力学性能,并实现与周围组织的有机整合。其中,材料-细胞的相互作用是组织再生材料的核心问题。组织再生材料表界面的物理结构和化学性能可以直接影响细胞的黏附、铺展、增殖、迁移和分化等行为,进而影响组织修复和再生的效果。多数组织和器官具有立体结构,并具有更为精细的微结构。因此,三维组织再生材料体系的构建及其微结构调控是另外一个重要问题。本文结合本课题组近年的工作,综合国内外最新研究成果,重点介绍了生物材料表界面物理结构和理化性质对微粒吞噬、细胞黏附的影响、梯度材料对细胞黏附和定向迁移的作用、3D水凝胶中的细胞迁移行为及特点,以及用于皮肤和软骨组织修复与再生的植入材料,最后对生物材料在组织再生中的研究与应用进行了展望。     

电活性导电聚合物在生物医学中的应用

以聚吡咯、聚噻吩和聚苯胺为代表的电活性导电聚合物(electroactive conducting polymers,ECP)已成为生物材料、组织工程及临床医学领域关注的焦点.目前研究主要集中在生物相容性、细胞及组织工程、蛋白质分离、DNA吸附修复、可控药物释放、生物传感器、神经探针等方面.ECP在神经细胞、脑细胞、心肌干细胞再生和功能调节,定向诱导组织器官的再生修复方面具有潜在的应用前景.本文主要综述了聚吡咯(PPy)和聚苯胺(PANi)在生物医学领域的研究进展,和电刺激对细胞生长和干细胞分化的影响,并建议了一些前景可观的相关研究方向.     

组织工程相关生物材料表面工程的研究进展

生物材料用作人工细胞外基质(ECM ) 在组织工程中占据重要位置。本文在分析细胞2生物材料表面相互作用的基础上, 从生物材料中的水、材料表面的形态、材料表面的特异性识别及生物材料诱发愈合等方面探讨了生物材料的复杂性。生物材料对细胞的影响是一个双向、动态过程, 起着调节细胞增殖和凋亡平衡的作用。基于生物材料对细胞生长的影响, 本文提出了生物材料表面生物仿生化以提高细胞亲和力,糖链团簇、糖脂质及材料表面蛋白质修饰以提高细胞特异性识别, 材料表面的自组装修饰以改善表面形态等观点。     

取向结构和梯度分布医用材料的制备及应用

组织器官缺损或功能损失是人类健康所面临的重大危害,具有特定结构和组成的再生医学材料是实现组织再生与修复的关键和物质基础。本文对具有取向结构和梯度分布的再生医学材料的制备方法及其生物学性能进行了综述。与传统的再生医学材料相比,取向结构使得细胞在支架中呈取向分布和生长,有利于营养物质及代谢产物的传递,可用于构建具有取向结构的三维组织。具有物理性能、化学组成、生物因子梯度分布的再生医学材料能够调控细胞在梯度方向的黏附、迁移和分化等行为。基于仿生学原理设计的具有取向结构和梯度分布的再生医学材料为缺损组织或器官的再生与修复提供了更适宜的微环境,可望获得更出色的再生修复效果。     

光化学反应在生物材料表面修饰中的应用

生物医用材料的表界面设计在组织工程、生物医疗器械、生物传感与检测、生物芯片等领域越来越重要,深入理解材料性质,尤其是表界面性质,对生物材料研发具有一定指导作用。在生物材料表界面修饰的各种方法中,光化学修饰方法简单高效,且具有时空可控性和非侵入性等优点,已成为生物材料表界面修饰中的热点研究领域之一。本综述在介绍近年来发展的生物材料表面光化学修饰方法的基础上,集中介绍其在组织再生材料(仿细胞外基质界面、硬度调控薄膜凝胶、图案化和梯度表面、光响应动态表面)、微液滴阵列表面、高通量生物芯片等领域的应用,并进一步展望了光化学表面修饰在生物医用界面研究中的关键挑战和发展方向。     

生物材料与细胞相互作用及表面修饰

生物材料用作人工细胞外基质(ECMs)在组织工程中起重要作用。生物材料表面的拓扑结构、亲水／疏水平衡、自由能、电荷状况、化学基团和生物特异性识别对材料／细胞相互作用有较大影响。生物材料表面与细胞的相互作用主要是细胞膜表面受体与生物材料表面配体间的相互分子识别,因此采用仿生修饰生物材料表面以提高细胞亲和性和特异性识别。本文对生物材料与细胞相互作用及表面修饰的技术方法进行了介绍。     

微纳米图案化表面对细胞行为的影响

在再生医学领域中,材料对细胞生长和组织修复的调节作用一直是极为关键的问题.随着表面图案化技术的发展,在材料表面制备规则、可控、种类多样的图案化区域成为可能,因而该技术被广泛应用于再生医学、组织工程以及细胞诊断等相关学科领域.通过微纳米表面图案化方法,改变材料的化学性质和拓扑结构,从而实现对细胞粘附、迁移、增殖、凋亡、基...     

骨组织工程支架材料研究进展*

骨在组织工程中得到了非常广泛、深入的研究.支架材料与许多可降解材料一起也在进行探索性研究.用于骨组织工程的生物材料可以是三维多孔的刚硬材料,也可以是可注射材料.本文从聚合物角度综述了骨组织工程对支架材料的基本要求,用于骨组织工程的可降解生物材料、支架材料的设计和制备技术以及支架材料的表面修饰等方面的研究进展.     

可吸收引导组织再生膜*

引导组织再生膜（guided tissue regeneration membrane, GTRM）由于能使组织修复再生能力得到最大程度的发挥而广泛应用于各种软硬组织的修复与再生研究及临床医学中。GTRM分为不可吸收与可吸收GTRM,与不可吸收GTRM相比,由于可吸收GTRM越来越多的优点而备受关注。本文阐述了几种常见的可吸收GTRM材料（以胶原为代表的天然生物材料,以聚酯为代表的合成高分子材料和以羟基磷灰石为代表的可降解无机物材料）及其可吸收GTRM在骨缺损、创伤敷料以及防黏连等领域中的主要应用进展,重点综述了可吸收GTRM的主要制备方法--静电纺丝、溶剂浇铸、相转化及其优缺点。     

光聚合水凝胶及其在组织工程中的应用

水凝胶是一种亲水性聚合物网络,可以溶胀大量水,其物理性质接近软组织.光聚合与传统的聚合方法相比,具有反应速率快、反应条件缓和、反应放热低等特点.因此,光聚合水凝胶广泛应用于生物医学领域.本文介绍了光聚合水凝胶材料,并详细论述了光聚合水凝胶在药物释放体系、组织工程支架材料、细胞受控生长、细胞微囊化和可注射水凝胶等方面的应用.可以预见光聚合水凝胶作为生物材料在组织工程及再生医学领域中具有良好的应用前景.     

Mass spectrometry based proteomic analysis of human stem cells: a brief review

Stem cells can give rise to various cell types and are capable of regenerating themselves over multiple cell divisions. Pluripotency and self-renewal potential of stem cells have drawn vast interest from different disciplines, with studies on the molecular properties of stem cells being one example. Current investigations on the molecular basis of stem cells pluripotency and self-renewal entail traditional techniques from chemistry and molecular biology. In this mini review, we discuss progress in stem cell research that employs proteomics approaches. Specifically, we focus on studies on human stem cells from proteomics perspective. To our best knowledge, only the following types of human stem cells have been examined via proteomics analysis: human neuronal stem cells, human mesenchymal stem cells, and human embryonic stem cells. Protein expression serves as biomarkers of stem cells and identification and expression level of such biomarkers are usually determined using two-dimensional electrophoresis coupled mass spectrometry or non-gel based mass spectrometry.     

Role of stem cell niche in body aging processes

Replacement of damaged differentiated cells by new cells due to the asymmetric division of stem cells can provide unlimited tolerance to degeneration of human tissues, if multipotent cells themselves are “immortal.” However, stem cells exist in a particular microenvironment (stem cell niche) and feel their negative impact with age, which attenuates the proliferate capacity of stem cells and leads to incorrect differentiation or, instead, uncontrolled division (promotion of tumor genesis). As a result, stem cell injection to elder persons will be not efficient, because “young” stem cell will engraft to the “old” niche. To sufficient increasing of lifespan, it is necessary to modify stem niche signals by injection of an additional quantity of required growth factors in well-defined proportions.     

Differentiation of human gingival mesenchymal stem cells into neuronal lineages in 3D bioconjugated injectable protein hydrogel construct for the management of neuronal disorder

The success of regeneration attempt is based on an ideal combination of stem cells, scaffolding and growth factors. Tissue constructs help to maintain stem cells in a required area for a desired time. There is a need for easily obtainable cells, potentially autologous stem cells and a biologically acceptable scaffold for use in humans in different difficult situations. This study aims to address these issues utilizing a unique combination of stem cells from gingiva and a hydrogel scaffold, based on a natural product for regenerative application. Human gingival mesenchymal stem cells (HGMSCs) were, with due induction, differentiated to neuronal lineages to overcome the problems associated with birth tissue-related stem cells. The differentiation potential of neuronal lineages was confirmed with suitable specific markers. The properties of mesenchymal stem cells in encapsulated form were observed to be similar to free cells. The encapsulated cells (3D) were then subjected to differentiation into neuronal lineages with suitable inducers, and the morphology and gene expression of transient cells were analyzed. HGMSCs was differentiated into neuronal lineages as both free and encapsulated forms without any significant differences. The presence of Nissl bodies and the neurite outgrowth confirm the differentiation. The advantages of this new combination appear to make it a promising tissue construct for translational application.     

The feasibility of using dielectrophoresis for isolation of glioblastoma subpopulations with increased stemness

Cancer stem cells (CSCs) are aggressive subpopulations with increased stem‐like properties. CSCs are usually resistant to most standard therapies and are responsible for tumor repropagation. Similar to normal stem cells, isolation of CSCs is challenging due to the lack of reliable markers. Antigen‐based sorting of CSCs usually requires staining with multiple markers, making the experiments complicated, expensive, and sometimes unreliable. Here, we study the feasibility of using dielectrophoresis (DEP) for isolation of glioblastoma cells with increased stemness. We culture a glioblastoma cell line in the form of neurospheres as an in vitro model for glioblastoma stem cells. We demonstrate that spheroid forming cells have higher expression of stem cell marker, nestin. Next, we show that dielectric properties of neurospheres change as a result of changing culture conditions. Our results indicate that spheroid forming cells need higher voltages to experience the same DEP force magnitude compared to normal monolayer cultures of glioblastoma cell line. This study confirms the possibility of using DEP to isolate glioblastoma stem cells.     

Strand displacement amplification for ultrasensitive detection of human pluripotent stem cells

Human pluripotent stem cells (hPSCs), such as embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs), provide a powerful model system for studies of cellular identity and early mammalian development, which hold great promise for regenerative medicine. It is necessary to develop a convenient method to discriminate hPSCs from other cells in clinics and basic research. Herein, a simple and reliable biosensor for stem cell detection was established. In this biosensor system, stage-specific embryonic antigen-3 (SSEA-3) and stage-specific embryonic antigen-4 (SSEA-4) were used to mark human pluripotent stem cells (hPSCs). Antibody specific for SSEA-3 was coated onto magnetic beads for hPSCs enrichment, and antibody specific for SSEA-4 was conjugated with carboxyl-modified tDNA sequence which was used as template for strand displacement amplification (SDA). The amplified single strand DNA (ssDNA) was detected with a lateral flow biosensor (LFB). This biosensor is capable of detecting a minimum of 19 human embryonic stem cells by a strip reader and 100 human embryonic stem cells by the naked eye within 80 min. This approach has also shown excellent specificity to distinguish hPSCs from other types of cells, showing that it is promising for specific and handy detection of human pluripotent stem cells.     

Vibrational spectroscopy differentiates between multipotent and pluripotent stem cells

Over the last few years, there has been an increased interest in the study of stem cells in biomedicine for therapeutic use and as a source for healing diseased or injured organs/tissues. More recently, vibrational spectroscopy has been applied to study stem cell differentiation. In this study, we have used both synchrotron based FTIR and Raman microspectroscopies to assess possible differences between human pluripotent (embryonic) and multipotent (adult mesenchymal) stem cells, and how O(2) concentration in cell culture could affect the spectral signatures of these cells. Our work shows that infrared spectroscopy of embryonic (pluripotent) and adult mesenchymal (multipotent) stem cells have different spectral signatures based on the amount of lipids in their cytoplasm (confirmed with cytological staining). Furthermore, O(2) concentration in cell culture causes changes in both the FTIR and Raman spectra of embryonic stem cells. These results show that embryonic stem cells might be more sensitive to O(2) concentration when compared to mesenchymal stem cells. While vibrational spectroscopy could therefore be of potential use in identifying different populations of stem cells further work is required to better understand these differences.     

Stem cells and their extracellular vesicles as natural and bioinspired carriers for the treatment of neurological disorders

One of the most explored strategies to cure neurological disorders is the transplantation of stem cells and their derived products. Different stem cells, as well as their extracellular vesicles (EV), modified or not, have been administrated in a large array of preclinical neurological disorder models. EV represent the hope of a “cell-free” therapy that would combine the therapeutic potential of stem cells without their drawbacks. Stem cells and EV showed various degrees of efficiency but, overall, provided benefits and improvements. The administration route has a considerable impact on stem cell and EV safety and therapeutic effect. However, despite evidences of preclinical success, the different strategies developed based on stem cells to treat neurological disorders do not exactly recapitulate in clinical trials. Discrepancies between preclinical and clinical experimental conditions and settings, cell availability and difficulties to scale up and to produce cells and EV in a Good Manufacturing Practices (GMP) environment limit translation.     

Control of Stem‐Cell Behavior by Fine Tuning the Supramolecular Assemblies of Low‐Molecular‐Weight Gelators

Controlling the behavior of stem cells through the supramolecular architecture of the extracellular matrix remains an important challenge in the culture of stem cells. Herein, we report on a new generation of low‐molecular‐weight gelators (LMWG) for the culture of isolated stem cells. The bola‐amphiphile structures derived from nucleolipids feature unique rheological and biological properties suitable for tissue engineering applications. The bola‐amphiphile‐based hydrogel scaffold exhibits the following essential properties: it is nontoxic, easy to handle, injectable, and features a biocompatible rheology. The reported glycosyl‐nucleoside bola‐amphiphiles (GNBA) are the first examples of LMWG that allow the culture of isolated stem cells in a gel matrix. The results (TEM observations and rheology) suggest that the supramolecular organizations of the matrix play a role in the behavior of stem cells in 3D environments.     

Effect of F68 on Cryopreservation of Mesenchymal Stem Cells Derived from Human Tooth Germ

The use of stem-cell-based therapies in regenerative medicine and in the treatment of disorders such as Parkinson, Alzheimer's disease, diabetes, spinal cord injuries, and cancer has been shown to be promising. Among all stem cells, mesenchymal stem cells (MSCs) were reported to have anti-apoptotic, immunomodulatory, and angiogenic effects which are attributed to the restorative capacity of these cells. Human tooth germ stem cells (HTGSCs) having mesenchymal stem cell characteristics have been proven to exert high proliferation and differentiation capacity. Unlike bone-marrow-derived MSCs, HTGSCs can be easily isolated, expanded, and cryopreserved, which makes them an alternative stem cell source. Regardless of their sources, the stem cells are exposed to physical and chemical stresses during cryopreservation, hindering their therapeutic capacity. Amelioration of the side effects of cryopreservation on MSCs seems to be a priority in order to maximize the therapeutic efficacy of these cells. In this study, we tested the effect of Pluronic 188 (F68) on HTGSCs during long-term cryopreservation and repeated freezing and defrosting cycles. Our data revealed that F68 has a protective role on survival and differentiation of HTGSCs in long-term cryopreservation.