Objective To review the research status of the neovascularization of adi pose tissue engineering in the past decade so as to provide theoretical references for the development of the rapid revascularization of tissue engineered adi pose. Methods The l iterature about the revascularization of adi pose tissue engineering was extensively reviewed andanalyzed, centering on 5 elements: specificity of histological structures and blood supply, revascularization mechanism, coculture of different seed cells, modification of scaffold, and microenvironment. Results Adi pose tissue engineering offers a new solution for soft tissue defects. However, there is still the unfulfilled need in the size of engineered adipose tissue (less than 1 mL), which was determined by the degree of neovascularization in engineered tissue. Overall, rapid neovascularization in engineering tissue is a key l ink of experimental study changing into cl inical appl ication. Conclusion Providing a sufficient supply with nutrients and oxygen by means of a sufficient and rapid neovascularization will be at the heart of any attempts to obtain bigger tissue engineered adipose to meet the demand of repairing large soft tissue defect.
Objective To investigate the possibility of theadipose tissue-derived stromal cells(ADSCs) to differentiate into the neuron-like cells and to explore a new cell source for the transplantation related to the central nervous system. Methods Adipose was digested by collagenase, cultured in the fetal bovine serum containing a medium. Trypse was used to digest the cells and the cell passage was performed. The 3rd to the 9th passage ADSCs were used to make an induction. Isobutylmethylxanthine, indomethacin, insulin, and dexamethasone were used to induce the ADSCs to differentiate into the neuron-like cells and adipocytes. Sudan black B and immunocytochemistry were used to identify the cells. Results A population of the ADSCs could be isolated from the adult human adipose tissue, they were processed to obtain a fibroblast-like population of the cells and could be maintained in vitro for an extendedperiod with the stable population doubling, and they were expanded as the undifferentiated cells in culture for more than 20 passages, which indicated their proliferative capacity. They expressed vimentin and nestin, and characteristics of the neuron precursor stem cells at an early stage of differentiation. And the majority of the ADSCs also expressed the neuron-specific enolase and βⅢ-tubulin, characteristics of the neurons. Isobutyl-methyxanthine, indomethacin, insulin, and dexamethasone induced 40%-50% of ADSCs to differentiate into adipocytes and 0.1%0.2% of ADSCs into neuron-like cells. The neuron-like cells had a complicated morphology of the neurons, and they exhibited a neuron phenotype, expressed nestin, vimentin, neuron-specific enolase and βⅢ-tubulin, but some neuron-like cells also expressed thesmooth muscle actin (SMA), and the characteristics of the smooth muscle cells; however, the neurons from the central nervous system were never reported to express this kind of protein. Therefore, the neuron-like cells from the ADSCs could be regarded as functional neurons. Conclusion Ourresults support the hypothesis that the adult adipose tissue contains the stem cells capable of differentiating into the neuron-like cells, and they can overcome their mesenchymal commitment, which represents an alternative autologous stemcell source for transplantation related to the central nervous system.
Objective To review research progress of adipose tissuederived stromal cells (ADSCs).Methods The recent articles on ADSCs were extensively reviewed, and the culture and differentiation ability of ADSCs were investigated.Results A population of stem cells could be isolated from adult adipose tissue, they were processed to obtain a fibroblast-like population of cells and could be maintained in vitro for extended periods with stable population doubling. The majority of the isolated cells were mesenchymal origin, with a few pericytes,endothelial cells and smooth muscle cells. ADSCs could be induced to differentiate intomultiple mesenchymal cell types, including osteogenic, chondrogenic, myogenic and adipogenic cells, they could also differentiate into nerve cells.Conclusion ADSCs can substitute mesenchymal stem cells and become an alternative stem cells source for tissue engineering.
ObjectiveTo study effect of expression levels of serum inflammatory factors and insulin receptor substrate(IRS)-1/2 in visceral adipose tissue after Roux-en-Y gastric bypass(RYGB) on type 2 diabetes mellitus(T2DM) rats, and explore possible mechanism in treatment of T2DM. MethodsThe T2DM rats models were established, which were divided into 3 groups by intervention: T2MD-RYGB group(n=14), T2MD-sham operation(T2MD-SO) group(n=10), and T2MD group(n=10), and 10 normal rats were selected as control group. The rats of the T2MD-RYGB group were received the RYGB, and of the T2MD-SO group were received transection and reanastomosis of the gastroin-testinal tract. The fasting plasma glucose(FPG), fasting insulin(FINS), C-reaction protein(CRP), tumor necrosis factor-α(TNF-α), free fatty acid(FFA), homestasis model assessment for insulin resistance(HOMA-IR), adipose tissue insulin resistance(Adipo-IR) were tested respectively before operation and on week 1, 4, 8 after operation(synchronous detec-tion of rats with or without surgical intervention). The IRS-1 and IRS-2 protein contents of the rat epididymal adipose tissue were tested on week 8 after operation. ResultsThe FPG, FINS, CRP, TNF-α, FFA levels, and HOMA-IR, Adipo-IR indexes in the T2DM rats were significantly higher than those in the normal rats(P < 0.05) before operation, the above indicators on week 4, 8 after operation were significantly lower than those before operation in the T2MD-RYGB group(P < 0.05). The differences of changes among the other groups were not statistically significant(P > 0.05). The IRS-1 and IRS-2 protein expressions in the adipose tissue of the rats were significantly increased in the T2MD-RYGB group as compared with these indicators in the T2MD group and T2MD-SO group(P < 0.05), but which were significantly lower than those in the control group(P < 0.05). ConclusionsRYGB could increase IRS-1/2 expression levels in adipose tissue, which could enhance insulin sensitivity, decrease serum inflammatory factors levels, and improve insulin resistance ultimately. This might be one of the mechanisms in treatment of T2DM.
ObjectiveTo summarize the isolation procedures, molecular characterization, and differentiation and vascularization capacity of adipose-derived stem cells (ADSCs), in order to discuss the potential value of ADSCs for the repairment and regeneration of adipose tissues. MethodsRelated literatures about ADSCs were retrieved to summarize the potential value of ADSCs for the repairment and regeneration of adipose tissues. ResultsAs mesenchymal stem cells, ADSCs was rich in human adipose tissues. ADSCs possessed the potential to differentiate toward a variety of cell lineages, such as adipogenic, chondrogenic, osteogenic, cardiomyogenic, myogenic, and angiogenic. Besides, its capacity of adipogenic differentiation could maintain several passages. The most importantly, ADSCs could secrete significant amounts of angiogenesis-related cytokines, such as vascular endothelial growth factor (VEGF) and fibroblast growth factor-2 (FGF-2), which increased the angiogenesis of adipose tissue. ConclusionsADSCs play a key role in adipose tissue engineering, autologous adipose tissue grafting, and soft tissue wound repairing, which have important application prospect for breast reconstruction.
ObjectiveTo prepare human acellular adipose tissue matrix and to evaluate the cellular compatibility so as to explore a suitable bio-derived scaffold for adipose tissue engineering. MethodsThe adipose tissue was harvested from abdominal skin graft of breast cancer patients undergoing radical mastectomy or modified radical mastectomy, and then was treated with a series of decellularization processes including repeated freeze-thaw, enzyme digestion, and organic solvent extraction. The matrix was examined by histology, immunohistochemistry, DAPI fluorescence staining, and scanning electron microscopy to observe the the removal of cells and to analyze its composition of collagen type IV, laminin, and fibronectin, and microstructure. The 3rd passage human adipose-derived stem cells (hADSCs) were co-cultured with acellular adipose tissue matrix and different concentrations of extracted liquid (100%, 75%, 50%, and 25%). The cytotoxic effects of the matrix were tested by MTT. The biocompatibility of the matrix was detected by live/dead staining and scanning electron microscopy observation. ResultsThe acellular adipose tissue matrix basically maintains intrinsical morphology. The matrix after acellular treatment consisted of extracellular matrix without any cell components, but there were abundant collagen type I; neither DNA nor lipid residual was detected. Moreover, the collagen was the main component of the matrix which was rich in laminin and fibronectin. At 1, 3, and 5 days after co-cultured with hADSCs, the cytotoxic effect of matrix was grade 0-1. The matrix displayed good cell compatibility and proliferation. ConclusionThe acellular adipose tissue matrix prepared by repeated freeze-thaw, enzyme digestion, and organic solvent extraction method remains abundant extracellular matrix and has good cellular compatibility, so it is expected to be an ideal bio-derived scaffold for adipose tissue engineering.
ObjectiveTo evaluate the mechanism of stromal vascular fraction (SVF) promoting angiogenesis and tissue regeneration in tissue engineering chamber. MethodsTwenty-four 6-month-old New Zealand white rabbits, male or female, weighing 2.5-2.8 kg, were selected. Thoracic dorsal arteriovenous bundle combined with collagen type I scaffold was transplanted to dorsal side, and wrapped by cylindrical hollow silicone chamber; all animals were randomly divided into the experimental group (n=12) and the control group (n=12). SVF was isolated from the back fat pads of rabbits in experimental group and labelled with DiI at 2 weeks after operation. The 1 mL cell suspension (1×106 cells/mL) and equal saline were injected into the chamber in experimental group and control group, respectively. The regenerative tissues were harvested for general observation and HE staining at 2 and 4 weeks after injection;and immunofluorescent staining was carried out in experimental group at 4 weeks. ResultsAt 2 weeks after injection, the regenerative tissue was cylindrical; obvious vessel network and incompletely degradable collagen scaffold could be seen on the surface of the new tissue in 2 groups. The volume of new tissue was (0.87±0.11) mL in experimental group, and (0.72±0.08) mL in control group at 2 weeks, showing significant difference (t=2.701, P=0.011). At 4 weeks, little collagen scaffold could be seen on the surface in control group, but no collagen scaffold in experimental group; the volume of new tissue was (0.74±0.14) mL in experimental group, and (0.64±0.10) mL in control group, showing no significant difference (t=1.424, P=0.093). HE staining showed new mature vessels at 4 weeks, but no adipose tissue or fat lobulus formed in both groups; the capillary density was significantly higher in experimental group than in control group at 2 weeks (t=6.291, P=0.000) and at 4 weeks (t=5.445, P=0.000). The immunofluorescent staining found that SVF survived and located at the edge area after 4 weeks; the expressions of CD31 and DiI were positive in some endothelial cells. ConclusionSVF can promote the angiogenesis and tissue regeneration in tissue engineering chamber, but it can not differentiate into adipocyte spontaneously without adipogenic microenvironment.
ObjectiveTo study the feasibility of human adipose-derived stem cells (hADSCs) combined with small intestinal submucosa powder (SISP)/chitosan chloride (CSCl)-β-glycerol phosphate disodium (GP)-hydroxyethyl cellulose (HEC) for adipose tissue engineering. MethodshADSCs were isolated from human breast fat with collagenase type I digestion, and the third passage hADSCs were mixed with SISP/CSCl-GP-HEC at a density of 1×106 cells/mL. Twenty-four healthy female nude mice of 5 weeks old were randomly divided into experimental group (n=12) and control group (n=12), and the mice were subcutaneously injected with 1 mL hADSCs+SISP/CSCl-GP-HEC or SISP/CSCl-GP-HEC respectively at the neck. The degradation rate was evaluated by implant volume measurement at 0, 1, 2, 4, and 8 weeks. Three mice were euthanized at 1, 2, 4, and 8 weeks respectively for general, histological, and immunohistochemical observations. The ability of adipogenesis (Oil O staining), angiopoiesis (CD31), and localized the hADSCs (immunostaining for human Vimentin) were identified. ResultsThe volume of implants of both groups decreased with time, but it was greater in experimental group than the control group, showing significant difference at 8 weeks (t=3.348, P=0.029). The general observation showed that the border of implants was clear with no adhesion at each time point;fat-liked new tissues were observed with capillaries on the surface at 8 weeks in 2 groups. The histological examinations showed that the structure of implants got compact gradually after injection, and SISP gradually degraded with slower degradation speed in experimental group;adipose tissue began to form, and some mature adipose tissue was observed at 8 weeks in the experimental group. The Oil O staining positive area of experimental group was greater than that of the control group at each time point, showing significant difference at 8 weeks (t=3.411, P=0.027). Immunohistochemical staining for Vemintin showed that hADSCs could survive at each time point in the experimental group;angiogenesis was most remarkable at 2 weeks, showing no significant differences in CD31 possitive area between 2 groups (P>0.05), but angiogenesis was more homogeneous in experimental group. ConclusionSISP/CSCl-GP-HEC can use as scaffolds for hADSCs to reconstruct tissue engineered adipose.
Objective To summarize the donor factors and experimental factors that affect adipogenic differentiation of adipose derived stem cells, so as to provide reference for adipogenic differentiation of adipose derived stem cells. Methods The related research literature about donor factors and experimental factors affecting adipogenic differentiation of adipose derived stem cells in recent years was extensively reviewed and summarized. Results There are a lot of donor factors and experimental factors affecting adipogenic differentiation of adipose derived stem cells, but some of the factors are still controversial, such as donor age, health status, adipose tissue of different parts, and so on. These factors need to be further studied. Conclusion The donor factors and experimental factors that affect adipogenic differentiation of adipose derived stem cells should be deeply studied and the controversial issues should be clarified to lay a solid foundation for the application of adipose derived stem cells in adipose tissue engineering.
ObjectiveTo summarize recent progress in adipose tissue acting as a more efficient and ideal therapy to facilitate wound repair and evaluate the therapeutic values of adipose tissue.MethodsThe related literature about adipose tissue for wound healing in recent years was reviewed and analyzed.ResultsEnormous studies focus on the capacity of adipose tissue to accelerate wound healing including cellular components, extracellular matrix, and paracrine signaling have been investigated.ConclusionAdipose tissue has generated great interest in recent years because of unique advantages such as abundant and accessible source, thriven potential to enhance the regeneration and repair of damaged tissue. However, there is still a need to explore the mechanism that adipose tissue regulates cellular function and tissue regeneration in order to facilitate clinical application of adipose tissue in wound healing.