A Novel Method of Human Adipose-Derived Stem Cell Isolation with Resultant Increased Cell Yield

Characterization and functional analysis of the adipose tissue-derived stromal vascular fraction of pediatric patients with osteogenesis imperfecta

Pediatric patients with Osteogenesis Imperfecta (OI), a heritable connective tissue disorder, frequently suffer from long bone deformations. Surgical correction often results in bone non-unions, necessitating revision surgery with autogenous bone grafting using bone-marrow-derived stem cells (BM-SC) to regenerate bone. BM-SC harvest is generally invasive and limited in supply; thus, adipose tissue's stromal vascular fraction (SVF) has been introduced as an alternative stem cell reservoir. To elucidate if OI patients' surgical site dissected adipose tissue could be used as autologous bone graft in future, we investigated whether the underlying genetic condition alters SVF's cell populations and in vitro differentiation capacity. After optimizing SVF isolation, we demonstrate successful isolation of SVF of pediatric OI patients and non-OI controls. The number of viable cells was comparable between OI and controls, with about 450,000 per gram tissue. Age, sex, type of OI, disease-causing collagen mutation, or anatomical site of harvest did not affect cell outcome. Further, SVF-containing cell populations were similar between OI and controls, and all isolated SVF's demonstrated chondrogenic, adipogenic, and osteogenic differentiation capacity in vitro. These results indicate that SVF from pediatric OI patients could be used as a source of stem cells for autologous stem cell therapy in OI.

Purification and characterization of human adipose-resident microvascular endothelial progenitor cells

Human adipose tissue is a rich source of adipose-derived stem cells (ASCs) and vascular endothelial progenitor cells (EPCs). However, no standardized method has been established for the isolation and purification of adipose-derived EPCs (AEPCs). The aim of this study was to establish a method for the isolation and purification of AEPCs. The stromal vascular fraction (SVF) was extracted from human lipoaspirates, and the CD45⁻CD31⁺ fraction of the SVF was collected by magnetic-activated cell sorting (MACS). The CD45⁻CD31⁺ fraction was cultured for 4.5 days, followed by a second MACS separation to collect the CD31⁺ fraction. Purified AEPCs were expanded without being overwhelmed by proliferating ASCs, indicating that a high level (> 95%) of AEPC purification is a key factor for their successful isolation and expansion. AEPCs exhibited typical endothelial markers, including CD31, von Willebrand factor, and the isolectin-B4 binding capacity. AEPCs formed colonies, comparable to cultured human umbilical vein endothelial cells (HUVECs). Both AEPCs and HUVECs formed capillary-like networks in the tube formation assay, with no significant difference in network lengths. We are the first to establish a purification and expansion method to isolate these cells. Because adipose tissue is a clinically accessible and abundant tissue, AEPCs may have potential advantages as a therapeutic tool for regenerative medicine.

Isolation and Characterization of Buccal Fat Pad and Dental Pulp MSCs from the Same Donor

Mesenchymal stem cells (MSCs) can be harvested from different sites in the oral cavity, representing a reservoir of cells useful for regenerative purposes. As direct comparisons between at least two types of MSCs deriving from the same patient are surprisingly rare in scientific literature, we isolated and investigated the osteoinductive potential of dental pulp stem cells (DPSCs) and buccal fat pad stem cells (BFPSCs). MSCs were isolated from the third molar dental pulp and buccal fat pads of 12 patients. The number of viable cells was quantified through manual count. Proliferation and osteodifferentiation assays, flow cytometry analysis of cell phenotypes, and osteocalcin release in vitro were performed. The isolation of BFPSCs and DPSCs was successful in 7 out of 12 (58%) and 3 out of 12 (25%) of retrieved samples, respectively. The yield of cells expressing typical stem cell markers and the level of proliferation were higher in BFPSCs than in DPSCs. Both BFP-SCs and DPSCs differentiated into osteoblast-like cells and were able to release a mineralized matrix. The release of osteocalcin, albeit greater for BFPSCs, did not show any significant difference between BFPSCs and DPSCs. The yield of MSCs depends on their site of origin as well as on the protocol adopted for their isolation. Our data show that BFP is a valuable source for the derivation of MSCs that can be used for regenerative treatments.

Adipose tissue-derived stem cells: a comparative review on isolation, culture, and differentiation methods

Adipose tissue-derived stem cells (ADSCs) are an available source of mesenchymal stem cells with the appropriate capacity to in vitro survive, propagate, and differentiate into cells from three lineages of ectoderm, mesoderm, and endoderm. The biological features of ADSCs depend on the donor physiology and health status, isolation procedure, culture conditions, and differentiation protocols used. Adipose tissue samples are provided by surgery and lipoaspiration-based methods and subjected to various mechanical and chemical digestion techniques to finally generate a heterogeneous mixture named stromal vascular fraction (SVF). ADSCs are purified through varied cell populations that exist within SVF and cultured under standard conditions to give rise to a highly rich resource of stem cells directly applied in the clinic or differentiated into a wide range of cells. The development and optimization of conventional isolation, expansion, and differentiation methods seem noteworthy to preserve the desirable biological functions of ADSCs in pre-clinical and clinical investigations.

Delivery of Human Stromal Vascular Fraction Cells on Nanofibrillar Scaffolds for Treatment of Peripheral Arterial Disease

Cell therapy for treatment of peripheral arterial disease (PAD) is a promising approach but is limited by poor cell survival when cells are delivered using saline. The objective of this study was to examine the feasibility of aligned nanofibrillar scaffolds as a vehicle for the delivery of human stromal vascular fraction (SVF), and then to assess the efficacy of the cell-seeded scaffolds in a murine model of PAD. Flow cytometric analysis was performed to characterize the phenotype of SVF cells from freshly isolated lipoaspirate, as well as after attachment onto aligned nanofibrillar scaffolds. Flow cytometry results demonstrated that the SVF consisted of 33.1 ± 9.6% CD45⁺ cells, a small fraction of CD45^–/CD31⁺ (4.5 ± 3.1%) and 45.4 ± 20.0% of CD45^–/CD31^–/CD34⁺ cells. Although the subpopulations of SVF did not change significantly after attachment to the aligned nanofibrillar scaffolds, protein secretion of vascular endothelial growth factor (VEGF) significantly increased by six-fold, compared to SVF cultured in suspension. Importantly, when SVF-seeded scaffolds were transplanted into immunodeficient mice with induced hindlimb ischemia, the cell-seeded scaffolds induced a significant higher mean perfusion ratio after 14 days, compared to cells delivered using saline. Together, these results show that aligned nanofibrillar scaffolds promoted cellular attachment, enhanced the secretion of VEGF from attached SVF cells, and their implantation with attached SVF cells stimulated blood perfusion recovery. These findings have important therapeutic implications for the treatment of PAD using SVF.

The cell yields and biological characteristics of stromal/stem cells from lipoaspirate with different digestion loading ratio

Effective harvesting procedure for adipose tissue is demanded by the affordable Good Manufacturing Practice-Compliant Production of clinical-grade adipose tissue-derived stem cells (hADSCs). Enzymatic digestion using collagenase is the most reliable method of adipose tissue-derived stem cells (hADSCs) isolation, while the optimized loading volume ratios of digestion to container during the shaking process of adipose tissue and collagenase mixture are still lacking. This study was conducted to determine the optimized loading volume ratio (mixture to container) for enzymatic digestion of Stromal/Stem Cells from lipoaspirate. Lipoaspirates were obtained from twelve women immediately after liposuction. Then tissue from each patient was divided into four groups according to different loading volume ratios in 50 ml centrifugal tube: 0.2 group, 0.4 group, 0.6 group, 0.8 group. Stromal vascular fractions (SVF) were obtained from each group, then total cell counts, viability and viable cell count were performed. hADSCs were harvested at passage (P) 2, whose morphologies, immunophenotypes, proliferation, and tri-differentiation abilities were compared. 0.4 loading volume ratio provided the highest cell yield, favorable viability and viable cell yield. The proliferation and triple differentiation ability of hADSCs obtained by 0.4 group was not inferior to that of other groups. Therefore, 0.4 may be the optimal loading volume ratio for hADSCs isolation from lipoaspirate by enzymatic digestion in current setting.

In Vitro and In Vivo Osteogenic Differentiation of Human Adipose-Derived Stromal Cells

Adipose-derived stromal cells (ASCs) are a promising population of cells that may be useful for the regeneration of human tissue defects. ASCs are capable of forming bone tissue in vitro and in vivo. Further work is required to determine the optimal conditions that will allow human ASCs to regenerate tissue in clinically significant tissue defects. Here we present three experimental protocols that are indispensable for the study of ASC osteogenic activity.

Human Adipose-Derived Stromal Cell Isolation Methods and Use in Osteogenic and Adipogenic In Vivo Applications

Adipose tissue represents an abundant and easily accessible source of multipotent cells, which may serve as excellent building blocks for tissue engineering. This article presents a newly described protocol for isolating adipose-derived stromal cells (ASCs) from human lipoaspirate, compared to the standard protocol for harvesting ASCs established in 2001. Human ASC isolation is performed using two methods, and resultant cells are compared through cell yield, cell viability, cell proliferation and regenerative potential. The osteogenic and adipogenic potential of ASCs isolated using both protocols are assessed in vitro and gene expression analysis is performed. The focus of this series of protocols is the regenerative potential of both cell populations in vivo. As such, the two in vivo animal models described are fat graft retention (soft tissue reconstruction) and calvarial defect healing (bone regeneration). The techniques described comprise fat grafting with cell assisted lipotransfer, and calvarial defect creation healed with cell-seeded scaffolds. © 2017 by John Wiley & Sons, Inc.