Collagenase Lot Selection and Purification for Adipose Tissue Digestion

In Vitro Study of a Novel Vibrio alginolyticus-Based Collagenase for Future Medical Application

Mesenchymal stem cells extracted from adipose tissue are particularly promising given the ease of harvest by standard liposuction and reduced donor site morbidity. This study proposes a novel enzymatic method for isolating stem cells using Vibrio alginolyticus collagenase, obtaining a high-quality product in a reduced time. Initially, the enzyme concentration and incubation time were studied by comparing cellular yield, proliferation, and clonogenic capacities. The optimized protocol was phenotypically characterized, and its ability to differentiate in the mesodermal lineages was evaluated. Subsequently, that protocol was compared with two Clostridium histolyticum-based collagenases, and other tests for cellular integrity were performed to evaluate the enzyme's effect on expanded cells. The best results showed that using a concentration of 3.6 mg/mL Vibrio alginolyticus collagenase allows extracting stem cells from adipose tissue after 20 min of enzymatic reaction like those obtained with Clostridium histolyticum-based collagenases after 45 min. Moreover, the extracted cells with Vibrio alginolyticus collagenase presented the phenotypic characteristics of stem cells that remain after culture conditions. Finally, it was seen that Vibrio alginolyticus collagenase does not reduce the vitality of expanded cells as Clostridium histolyticum-based collagenase does. These findings suggest that Vibrio alginolyticus collagenase has great potential in regenerative medicine, given its degradation selectivity by protecting vital structures for tissue restructuration.

Culture of Mesenchymal Stem Cells Derived From the Infrapatellar Fat Pad Without Enzyme and Preliminary Study on the Repair of Articular Cartilage Defects in Rabbits

Objective: The aim of the study was to evaluate the advantages of without enzyme isolating patellar fat pad-derived mesenchymal stem cells (IPFP-SCs) and the feasibility of cartilage repair.

Methods: The IPFP-SCs were isolated using the without enzyme method and compared with the IPFP-SCs obtained by the traditional enzyme digestion method in terms of cell proliferation ability, characterization, and differentiation ability, and the differences in chondrogenic induction and differentiation between the two groups were compared. Twenty-four New Zealand rabbits were randomly divided into four groups (n = 6). After the articular cartilage defects were modeled, different preparations were injected into the joint cavity. The rabbits in the group A were injected with the mixture of IPFP-SCs and pure PRP (P-PRP), separated using the without enzyme method, while those in the group B were injected with the mixture of IPFP-SCs and P-PRP separated with the digestion method, while those in the group C were injected with SVF separated using the without enzyme method, and those in the group D were injected with normal saline. At 6 weeks and 12 weeks after operation, the cartilage repair of rabbit joint specimens was observed and evaluated by gross observation and histological staining, and the effects of different IPFP-SCs application forms in repairing cartilage defects were compared.

Results: The time required to obtain IPFP-SCs by enzyme-free isolation was significantly less than that by enzyme digestion, while the acquisition rate of primary cells was significantly lower than that by enzyme digestion. After culture and amplification, the two IPFP-SCs from different sources did not show significant differences in cell proliferation, cell phenotype, and differentiation ability. In animal experiments, groups A and B had the best effect on the repair of cartilage defects, and there was no significant difference between the two groups. The repair effect in group C was weaker than that in the former two groups, but it was relatively better than that in group D.

Conclusion: It is more time-saving to obtain IPFP-SCs by the without enzyme method than by enzymatic digestion, and there is no significant difference in cell identification and differentiation potential between the two methods. However, the rate of obtaining primary cells was significantly lower than that with the enzyme digestion method. IPFP-SCs showed good repair effect in the rabbit animal cartilage defect model, providing ideas and reference for the clinical application of stem cells in repairing articular cartilage.

Vascularization of Microvascular Fragment Isolates from Visceral and Subcutaneous Adipose Tissue of Mice

Background:

Adipose tissue-derived microvascular fragments (MVF) represent effective vascularization units for tissue engineering. Most experimental studies in rodents exclusively use epididymal adipose tissue as a visceral fat source for MVF isolation. However, in future clinical practice, MVF may be rather isolated from liposuctioned subcutaneous fat tissue of patients. Therefore, we herein compared the vascularization characteristics of MVF isolates from visceral and subcutaneous fat tissue of murine origin.

Methods:

MVF isolates were generated from visceral and subcutaneous fat tissue of donor mice using two different enzymatic procedures. For in vivo analyses, the MVF isolates were seeded onto collagen-glycosaminoglycan scaffolds and implanted into full-thickness skin defects within dorsal skinfold chambers of recipient mice.

Results:

By means of the two isolation procedures, we isolated a higher number of MVF from visceral fat tissue when compared to subcutaneous fat tissue, while their length distribution, viability and cellular composition were comparable in both groups. Intravital fluorescence microscopy as well as histological and immunohistochemical analyses revealed a significantly reduced vascularization of implanted scaffolds seeded with subcutaneous MVF isolates when compared to implants seeded with visceral MVF isolates. Light and scanning electron microscopy showed that this was due to high amounts of undigested connective tissue within the subcutaneous MVF isolates, which clogged the scaffold pores and prevented the interconnection of individual MVF into new microvascular networks.

Conclusion:

These findings indicate the need for improved protocols to generate connective tissue-free MVF isolates from subcutaneous fat tissue for future translational studies.

Isolation and culture of putative mesenchymal stem cells from equine umbilical cord Wharton’s jelly

Despite major progress and knowledge related to the application of adult stem cells, finding alternative sources for bone marrow MSCs has remained a challenge in both humans and animals. In the current study, two protocols namely sequential enzymatic tissue digestion and tissue explant techniques were tried for successful establishment of MSC culture. Umbilical tissues were isolated each time of foaling from five sequential foalings of Marwari mares. Total cell yield, their growth potential and cryopreservation potential were studied. Adherent cell colonies could be established using both isolation methods. Both the cell populations yielded from different protocols performed similarly in terms of population doubling and CFU number value. Additionally, the cells proliferated vigourously and displayed a similar morphology of mesenchymal stem cells. The MSCs were plastic adherent, colonogenic and their morphology was polygonal and fibroblast like. During the proliferation, the cells exhibited density dependent inhibition; analysis of microbial contamination from bacteria, mycoplasma and fungi were negative; the population doubling time of the MSCs isolated was 34.8 h and 40.2 h in enzymatic treatment and tissue explant methods respectively, and diploid chromosome number of the cells was 64, and the diploid frequency was higher than 80%. In conclusion, this study reveals that both the techniques proved to be non-invasive, efficient, simple and quick for isolation and establishment of MSC culture of extra embryonic tissues from equines.

Adipose-Derived Mesenchymal Stem Cells in the Use of Cartilage Tissue Engineering: The Need for a Rapid Isolation Procedure

Mesenchymal stem cells (MSCs) have shown much promise with respect to their use in cartilage tissue engineering. MSCs can be obtained from many different tissue sources. Among these, adipose tissue can provide an abundant source of adipose-derived mesenchymal stem cells (ADMSCs). The infrapatellar fat pad (IFP) is a promising source of ADMSCs with respect to producing a cartilage lineage. Cell isolation protocols to date are time-consuming and follow conservative approaches that rely on a long incubation period of 24–48 hours. The different types of ADMSC isolation techniques used for cartilage repair will be reviewed and compared with the view of developing a rapid one-step isolation protocol that can be applied in the context of a surgical procedure.

Isolation of Murine Adipose-Derived Stromal/Stem Cells Using an Explant Culture Method

Adipose tissue provides valuable cell source for tissue engineering, regenerative medicine, and adipose tissue biology studies. The most widely used adipose-derived stromal/stem cells (ASCs) isolation protocol involves enzymatic digestion with collagenase. However, the yield of the method is poor even impossible to collect enough stromal vascular fraction (SVF) for expansion when the sample size is small, for instance only new born mice is available for cell culture. Here, we describe an efficient protocol for the isolation and expansion of ASCs using explant culture.

The efficacy and safety of platelet-rich plasma and adipose-derived stem cells: an update

During the past decade, many studies using platelet-rich plasma (PRP) or adipose-derived stem cells (ASCs) have been conducted in various medical fields, from cardiovascular research to applications for corneal diseases. Nonetheless, there are several limitations of practical applications of PRP and ASCs. Most reports of PRP are anecdotal and few include controls to determine the specific role of PRP. There is little consensus regarding PRP production and characterization. Some have reported the development of an antibody to bovine thrombin, which was the initiator of platelet activation. In the case of ASCs, good manufacturing practices are needed for the production of clinical-grade human stem cells, and in vitro expansion of ASCs requires approval of the Korea Food and Drug Administration, such that considerable expense and time are required. Additionally, some have reported that ASCs could have a potential risk of transformation to malignant cells. Therefore, the authors tried to investigate the latest research on the efficacy and safety of PRP and ASCs and report on the current state and regulation of these stem cell-based therapies.

Potential for neural differentiation of mesenchymal stem cells

Adult human stem cells have gained progressive interest as a promising source of autologous cells to be used as therapeutic vehicles. Particularly, mesenchymal stem cells (MSCs) represent a great tool in regenerative medicine because of their ability to differentiate into a variety of specialized cells. Among adult tissues in which MSCs are resident, adipose tissue has shown clear advantages over other sources of MSCs (ease of surgical access, availability, and isolation), making adipose tissue the ideal large-scale source for research on clinical applications. Stem cells derived from the adipose tissue (adipose-derived stem cells = ADSCs) possess a great and unique regenerative potential: they are self-renewing and can differentiate along several mesenchymal tissue lineages (adipocytes, osteoblasts, myocytes, chondrocytes, endothelial cells, and cardiomyocytes), among which neuronal-like cells gained particular interest. In view of the promising clinical applications in tissue regeneration, research has been conducted towards the creation of a successful protocol for achieving cells with a well-defined neural phenotype from adipose tissue. The promising results obtained open new scenarios for innovative approaches for a cell-based treatment of neurological degenerative disorders.

Fibrin matrix-supported three-dimensional organ culture of adipose tissue for selective outgrowth, expansion, and isolation of adipose-derived stem cells

Conventional systems for isolating adipose-derived stem cells (ASC) require enzymatic digestion of adipose tissue (AT), followed by monolayer culture to the enrich the stem cell population. However, these systems are hindered by low cell yields and a lack of reproducibility. The present study was aimed at developing a unique strategy for isolating ASC based on fibrin matrix-supported three-dimensional (3-D) organ culture of native AT. Furthermore, we tried to optimize the fibrin composition by adjusting the fibrinogen and thrombin concentrations to allow rapid outgrowth and proliferation of ASC in the 3-D fibrin matrix. Human cutaneous AT fragments were encapsulated within the fibrin matrix to construct a 3-D environment and cultured under dynamic conditions. During in vitro culture the fibrin matrix provided physical support for the AT and also allowed selective outgrowth of ASC from embedded AT fragments. In situ expanded outgrown cells were recovered from the fibrin matrix by selective fibrinolysis and propagated under monolayer culture conditions. The cultured cells fulfilled the following criteria for ASC: adhesion to culture plastic, multipotent differentiation, correct immunophenotypic profile. Fibrin matrix-supported 3-D organ culture produced ASC that with high competency in terms of growth and differentiation capabilities, and resulted in a larger and more consistent cell yield than obtained with conventional culture systems. The fibrinogen and thrombin concentrations inversely affected spreading, migration, and ASC outgrowth from native AT. Our results indicate that this 3-D organ culture system for AT can be used as an efficient and reproducible method for ASC isolation.

Concise review: Adipose-derived stromal vascular fraction cells and stem cells: let's not get lost in translation

Subcutaneous fat has emerged as an alternative tissue source for stromal/stem cells in regenerative medicine. Over the past decade, international research efforts have established a wealth of basic science and preclinical evidence regarding the differentiation potential and regenerative properties of both freshly processed, heterogeneous stromal vascular fraction cells and culture expanded, relatively homogeneous adipose-derived stromal/stem cells. The stage has been set for clinicians to translate adipose-derived cells from the bench to the bedside; however, this process will involve "development" steps that fall outside of traditional "hypothesis-driven, mechanism-based" paradigm. This concise review examines the next stages of the development process for therapeutic applications of adipose-derived cells and highlights the current state of the art regarding clinical trials. It is recommended that the experiments addressing these issues be reported comprehensively in the peer-review literature. This transparency will accelerate the standardization and reproducibility of adipose-derived cell therapies with respect to their efficacy and safety.

Adipose tissue-derived stem cells: characterization and potential for cardiovascular repair

Experimental studies have shown that cardiac transfer of unfractionated or partially purified bone marrow cells, as well as stem cells and progenitor cells derived from the bone marrow or peripheral blood, can enhance functional recovery after an acute myocardial infarction. However, the relatively low abundance, small tissue volume, difficult accessibility, and disease-related malfunction of bone marrow-derived stem cells hamper their clinical usefulness. Numerous studies have provided evidence that stromal cells derived from the adipose tissue (adipose tissue-derived stromal cells [ADSCs]) contain a population of adult multipotent mesenchymal stem cells and endothelial progenitor cells that can differentiate into several lineages, including endothelial cells, smooth muscle cells, and cardiomyocytes. The similarities between stem cells extracted from the bone marrow and the adipose tissue suggest the potential for the adipose tissue to act as an alternative, and perhaps preferable, cell source for repairing damaged tissues, such as the ischemic or infarcted heart. We have here reviewed the medical literature describing molecular and functional characterization, differentiation, potential role, and results obtained so far using ADSCs in tissue repair, with a particular focus on the role for ADSCs in cardiovascular repair and regeneration.

Comparative analysis of highly defined proteases for the isolation of adipose tissue-derived stem cells

BACKGROUND

Before the potential of adipose tissue-derived stem cells can fully be exploited for a broad scope of tissue-engineering and cell-based therapeutical applications, an effective and reproducible method for isolation is needed.

AIM

To comparatively analyze five highly defined protease formulations, Blendzyme 1-4, liberase H1 and a crude collagenase mixture in the course of digestion that consisted of three 1-h intervals.

METHODS

The resulting digests of human adipose tissue aspirates were evaluated for the yield of nucleated cells, viability and frequency of specific lineages, in particular CD90, CD34 and CD45, by flow cytometry. The functionality of the cells was assessed as to the colony-forming capacity in limiting dilution assays.

RESULTS

Based on all evaluation criteria, Blendzymes 1 and 2 and liberase H1 demonstrated a superior performance and highest consistency. Blendzyme 3 clearly underperformed compared with all other enzymes, and the performance of the rest of enzymes appeared erratic. As for the length of digestion, a 2-h interval appeared optimal when weighing both the yield and functionality of the cells in the stromal vascular fractions obtained from different adipose tissue samples.

CONCLUSION

Our results demonstrate that the highly purified proteases provide a valuable alternative to crude collagenase preparations, especially in scenarios where a high definition and reproducibility of the digestion process is of importance.

Adipose-derived stem cells for regenerative medicine

The emerging field of regenerative medicine will require a reliable source of stem cells in addition to biomaterial scaffolds and cytokine growth factors. Adipose tissue represents an abundant and accessible source of adult stem cells with the ability to differentiate along multiple lineage pathways. The isolation, characterization, and preclinical and clinical application of adipose-derived stem cells (ASCs) are reviewed in this article.

Improved enzymatic isolation of fibroblasts for the creation of autologous skin substitutes

The number of medical applications using autologous fibroblasts is increasing rapidly. We investigated thoroughly the procedure to isolate cells from skin using the enzymatic tissue dissociation procedure. Tissue digestion efficiency, cell viability, and yield were investigated in relation to size of tissue fragments, digestion volume to tissue ratio, digestion time, and importance of other protease activities present in Clostridium histolyticum collagenase (CHC) (neutral protease, clostripain, and trypsin). The results showed that digestion was optimal with small tissue fragments (2-3 mm3) and with volumes tissue ratios > or =2 ml/g tissue. For incubations < or =10 h, the digestion efficiency and cell isolation yields were significantly improved by increasing the collagenase, neutral protease, or clostripain activity, whereas trypsin activity had no effects. However, a too high proteolytic activity of one of the proteases present in CHC digestion solution or long exposure times interfered with cell viability and cell culture yields. The optimal range of CHC proteases activities per milliliter digestion solutions was determined for digestions < or =10 h (collagenase 2700-3900 Mandl U/ml, neutral protease 5100-10,000 caseinase U/ml, and clostripain 35-48 BAEE U/ml) and for longer digestions (>14 h) (collagenase 1350- 3000 U/ml, neutral protease 2550-7700 U/ml, and clostripain 18-36 U/ml). Using these conditions, a maximum fibroblast expansion was achieved when isolated cells were seeded at 1 x 10(4) cells/cm2. These results did not only allow selection of optimal CHC batches able to digest dermal tissue with an high cell viability but also significantly increased the fibroblast yields, enabling us to produce autologous dermal tissue in a clinically acceptable time frame of 3 wk.