黄瓜子叶身与子叶柄的生理特性差异及其不同培养反应

与黄瓜子叶身相比,无论是子叶离体培养前还是离体培养后, 在苗龄 3d～ 9d其间,子叶柄始终具有较低的呼吸强度和较大的 A260nm物质渗漏 ,而且,两者间差异随苗龄而改变,这表明子叶柄和子叶身的细胞透性、呼吸活性存在显著差异,这些差异可能与子叶离体培养时只有子叶柄部位才能分化花芽有某种联系.     

Raman Spectroscopy Based Techniques in Tissue Engineering—An Overview

Abstract: This article reviews the most recent applications of Raman spectroscopy (RS) in tissue engineering and regenerative medicine (TERM). Raman spectroscopy can potentially alleviate the current lack of capabilities to capture important biological data beyond the standard metabolite and pH indicators in tissue bioreactors. Key process components in bioreactors that are important to evaluate cellular integrity and functionality of tissue-engineered constructs include cells, scaffolds, and proteins. A number of studies are discussed to highlight the capability of RS in noninvasive, nondestructive, and label-free in situ analysis. Protein detection is emphasized due to the urgent need for faster and cheaper techniques. The extensiveness of protein detection studies and the inadequacy of current technology formulate the basis for detailing relevant methods seeking to improve the detection limit, specificity, or multiplexing performance of RS. We argue that RS has great promise to solve the key problem in tissue bioprocessing, namely, inadequate monitoring capabilities that handicap TERM from rising to prevalence in clinical practice.     

Analysis of feasibility of in vitro nuclear magnetic resonance tracking human umbilical cord mesenchymal stem cells by Gd-DTPA labeled

Objective

Three different kinds of transfection reagents were used to mediate the transfection of gadolinium-diethylenetriamine penta-acetic acid (Gd-DTPA) into human umbilical-cord-derived mesenchymal stem cells (hUCMSCs). The efficacy of different transfection reagents and the feasibility of NMR tracer in vitro of magnetized stem cells were estimated.

Methods

After purification by tissue explants adherent method, the biological characteristics of hUCMSCs in vitro were identified by subculture and amplification. Calcium phosphate, Effectene and liposome2000 were used to transfect Gd-DTPA-labeled hUCMSCs respectively, and cell counting was used to mediate the transfection of Gd-DTPA into hUCMSCs, which were then induced to lipoblast and osteoblast in vitro. The determination of the transfection activities of the transfection reagents was conducted by measuring the magnetic resonance imaging (MRI) signal intensity of the Gd-DTPA-labeled cells and the concentration of gadolinium ion in the cells. Furthermore, the relationship between the signal intensity of Gd-DTPA-labeled hUCMSCsMRI, cell subculture and generations was studied.

Results

Primary cells were obtained by tissue explants adherent for two weeks. The cells displayed a long spindle form and grew in swirl. After two passage generations, the cellular morphology became more homogeneous. The result detected by the flow cytometer showed that CD29C, D44, CD90, and CD105 were highly expressed, while no CD45, CD40, and HLA-DR expression was detected in the third generation cells. Directional induction in vitro caused the differentiation into lipoblast and osteoblast. After transfected by calcium phosphate, Effectene and liposome 2000, the signal intensity of stem cells was 2281.2 ± 118.8, 2031.9 ± 59.7 and 1887.4 ± 40.8 measured by MRI. Differences between these three groups were statistically significant (P < 0.05). The concentrations of gadolinium ion in three groups of stem cells were 0.178 ± 0.009 mg/L, 0.158 ± 0.003 mg/L and 0.120 ± 0.002 mg/L respectively, examined by inductively coupled plasma atomic emission spectrometry. No significant differences were found among these three groups (P < 0.05). The proliferation and differentiation abilities of the Gd-DTPA-labeled stem cells were not affected. A minimum 5 × 10⁴ Gd-DTPA-labeled stem cells could be traced with MRI in vitro and presented in high signal. The trace duration time in vitro was about 12 days.

Conclusions

Tissue explants adherent method can be availably applied to purify hUCMSCs. The Effectene method was proved to have the best transfection effect. The proliferation ability and differentiation potency of Gd-DTPA-labeled hUCMSCs were not affected, and the NMR of labeled stem cells in vitro was proved to be feasible.     

Mesenchymal stem cells: environmentally responsive therapeutics for regenerative medicine

Mesenchymal stem cells (MSCs) are partially defined by their ability to differentiate into tissues including bone, cartilage and adipose in vitro, but it is their trophic, paracrine and immunomodulatory functions that may have the greatest therapeutic impact in vivo. Unlike pharmaceutical treatments that deliver a single agent at a specific dose, MSCs are site regulated and secrete bioactive factors and signals at variable concentrations in response to local microenvironmental cues. Significant progress has been made in understanding the biochemical and metabolic mechanisms and feedback associated with MSC response. The anti-inflammatory and immunomodulatory capacity of MSC may be paramount in the restoration of localized or systemic conditions for normal healing and tissue regeneration. Allogeneic MSC treatments, categorized as a drug by regulatory agencies, have been widely pursued, but new studies demonstrate the efficacy of autologous MSC therapies, even for individuals affected by a disease state. Safety and regulatory concerns surrounding allogeneic cell preparations make autologous and minimally manipulated cell therapies an attractive option for many regenerative, anti-inflammatory and autoimmune applications.     

Stem cell implantation for osteonecrosis of the femoral head

What is the most effective treatment for the early stages of osteonecrosis of the femoral head? We assessed multiple drilling and stem cell implantation to treat the early stages of osteonecrosis of the femoral head. We report the clinical and radiological results of stem cell implantation and core decompression. In total, 128 patients (190 hips) who had undergone surgery were divided into two groups based on which treatment they had received: (1) multiple drilling and stem cell implantation or (2) core decompression, curettage and a bone graft. The clinical and radiographic results of the two groups were compared. At 5-year follow-up, in the stem cell implantation group, 64.3% (27/42) of the patients with Stage IIa disease, 56.7% (21/37) of the patients with Stage IIb disease and 42.9% (21/49) of the patients with Stage III disease had undergone no additional surgery. In the conventional core decompression group, 64.3% (9/14) of the patients with Stage IIa disease, 55.6% (5/9) of the patients with Stage IIb disease and 37.5% (3/8) of the patients with Stage III disease had undergone no additional surgery. Success rates were higher in patients with Ficat Stage I or II lesions than in those with Stage III lesions. There were no statistically significant differences between the groups in terms of success rate or in the clinical and radiographic results of the two methods. Essentially the same results were found with stem cell implantation as with the conventional method of core decompression.     

Amyloid-β oligomers regulate the properties of human neural stem cells through GSK-3β signaling

Alzheimer''s disease (AD) is the most common cause of age-related dementia. The neuropathological hallmarks of AD include extracellular deposition of amyloid-β peptides and neurofibrillary tangles that lead to intracellular hyperphosphorylated tau in the brain. Soluble amyloid-β oligomers are the primary pathogenic factor leading to cognitive impairment in AD. Neural stem cells (NSCs) are able to self-renew and give rise to multiple neural cell lineages in both developing and adult central nervous systems. To explore the relationship between AD-related pathology and the behaviors of NSCs that enable neuroregeneration, a number of studies have used animal and in vitro models to investigate the role of amyloid-β on NSCs derived from various brain regions at different developmental stages. However, the Aβ effects on NSCs remain poorly understood because of conflicting results. To investigate the effects of amyloid-β oligomers on human NSCs, we established amyloid precursor protein Swedish mutant-expressing cells and identified cell-derived amyloid-β oligomers in the culture media. Human NSCs were isolated from an aborted fetal telencephalon at 13 weeks of gestation and expanded in culture as neurospheres. Human NSCs exposure to cell-derived amyloid-β oligomers decreased dividing potential resulting from senescence through telomere attrition, impaired neurogenesis and promoted gliogenesis, and attenuated mobility. These amyloid-β oligomers modulated the proliferation, differentiation and migration patterns of human NSCs via a glycogen synthase kinase-3β-mediated signaling pathway. These findings contribute to the development of human NSC-based therapy for AD by elucidating the effects of Aβ oligomers on human NSCs.     

A Long‐Living Bioengineered Neural Tissue Platform to Study Neurodegeneration

The prevalence of dementia and other neurodegenerative diseases continues to rise as age demographics in the population shift, inspiring the development of long‐term tissue culture systems with which to study chronic brain disease. Here, it is investigated whether a 3D bioengineered neural tissue model derived from human induced pluripotent stem cells (hiPSCs) can remain stable and functional for multiple years in culture. Silk‐based scaffolds are seeded with neurons and glial cells derived from hiPSCs supplied by human donors who are either healthy or have been diagnosed with Alzheimer's disease. Cell retention and markers of stress remain stable for over 2 years. Diseased samples display decreased spontaneous electrical activity and a subset displays sporadic‐like indicators of increased pathological β‐amyloid and tau markers characteristic of Alzheimer's disease with concomitant increases in oxidative stress. It can be concluded that the long‐term stability of the platform is suited to study chronic brain disease including neurodegeneration.