Energy metabolic configuration of human adipose tissue- derived cells and its changes due to in vitro culture with osteogenic and adipogenic differentiation

Background: In recent years the therapeutic application of extracted adipose tissue for autologous fat grafting and the application of adipose tissue-derived mesenchymal stem cells (adMSC) isolated thereof has progressed. Water-jet assisted liposuction (WAL) is 1 procedure for harvesting adipose tissue and provides a favorable aesthetic outcome combined with high tissue protection. Tissue aspirated by WAL has been successfully applied in grafting procedures. Objectives: The aims of this study were to confirm the tissue viability and to understand the abundance and mesenchymal differentiation capacity of stem cells within the tissue. Methods: We analyzed tissue integrity of WAL tissue particles via fluorescence microscopy. The adMSC content was determined by isolating the cells from the tissue. The mesenchymal differentiation capacity was confirmed with cytochemical staining methods. Results: The stromal vascular fraction of WAL tissue showed high viability and contained an average of 2.6 × 105 CD34-positive cells per milliliter of tissue. Thus WAL tissue contains a high number of stem cells. Furthermore adMSC isolated from WAL tissue showed typical mesenchymal differentiation potential. Conclusions: WAL of adipose tissue is well suited for autologous fat grafting because it retains tissue viability. Furthermore it is a valid source for the subsequent isolation of adMSC with multipotent differentiation potential. Level of Evidence: 3 Accepted for publication April 6, 2015. Therapeutic Through the therapeutic application of extracted adipose tissue for autologous fat grafting, liposuction has become an important issue.1,2 In this context the properties of the aspirated tissue, like tissue particle size, viability, adipocytes number, and other adipose-resident cell types or functional structures (eg, blood vessels) need to be investigated in closer detail. Adipose tissue is composed of various cell types (adipocytes, endothelial cells, fibroblasts, blood and blood-derived cells, and adipose tissue-derived mesenchymal stem cells [adMSC]). 3-6 Enzymatic digestion of the adipose tissue and depletion of adipocytes yields the so-called stromal vascular fraction (SVF), which already has successfully been used in Mrs Meyer and Mrs Herzmann are PhD Students, Dr Salamon is a Post-doctoral Fellow, Mrs Adam is a Technical Assistant, and Dr Peters is Head of the Stem Cell Biology Group, Department of Cell Biology, Rostock University Medical Center, Rostock, Germany. Dr Kleine is on the Executive Board of Seracell Stammzelltechnologie GmbH, Rostock, Germany. Dr Matthiesen is Head of the Department of Medical Affairs, human med AG, Schwerin, Germany. Dr Ueberreiter is a Plastic Surgeon in private practice in Birkenwerder, Germany. Corresponding Author: Dr Kirsten Peters, Department of Cell Biology, Rostock University Medical Center, Schillingallee 69, 18057 Rostock, Germany. E-mail: kirsten.peters@med.uni-rostock.de 2 Aesthetic Surgery Journal different clinical approaches such as supplementation of fat grafts and treatment of urinary incontinence and chronic wounds.7-10 Zuk et al were the first to describe adMSC.6 By their intrinsic capacity for self-renewal and multipotent mesenchymal differentiation, adMSC are important in tissue homeostasis and regeneration.11 Human adMSC were shown to directly differentiate into osteoblasts and endothelial cells in a nonunion fracture model.12 In case studies, human adMSC were already successfully used to treat critical-size calvaria13 and maxilla defects.14 Furthermore, adMSC were demonstrated to engraft at long-term at the transplantation site.15,16 Compared with bone marrow, adipose tissue can be harvested in higher amounts, with a higher abundance of stem cells and less donor-site morbidity.17 adMSC are present at a concentration of roughly 50,000 cells per mL adipose tissue (approximately 7% of the cells found in enzymedissolved adipose tissue),18,19 which is 100-fold higher than found for mesenchymal stem cells (MSC) isolated from bone marrow.17 Also, the use of adult stem cells does not entail the ethical concerns that the use of embryonic stem cells does. Finally adMSC fulfill all MSC characteristics defined by the International Society for Cellular Therapy, the International Federation of Adipose Therapeutics and Sciences, and others.20,21 Adipose tissue can be harvested by various methods, such as resection, conventional liposuction, syringe-aspiration, and others.2 The specific liposuction methodology applied may impact the viability of cells present in the harvested tissue.22,23 Water jet-assisted liposuction (WAL) is a liposuction procedure that applies the tumescent solution as a thin, fan-shaped, targeted, pulsating jet.24,25 The cannula used during the operation comprises 2 channels that make it possible to infiltrate the tumescent solution and aspirate the emerging water and fat suspension at the same time. Thus, the amount of fluid infiltrated into the patient is much lower than during conventional liposuction procedures, which lowers the risk of cardiovascular side effects. This aims at ensuring the desired aesthetic outcome and safety of the patient as well as protecting the harvested adipose tissue. Our examinations assure quality of autologous fat grafts obtained by WAL and show differentiation reliability of mesenchymal stem cells isolated from WAL tissue. To this end, we examined the viability, number and adipogenic or osteogenic differentiation potential of adMSC isolated from WAL-harvested adipose tissue.