Biological Alchemy: Engineering Bone and Fat From Fat-Derived Stem Cells

Abstract

Adipose tissue contains a population of pluripotent stem cells capable of differentiating along multiple mesenchymal cell lineages. In this study the authors isolated these fat-derived stem cells successfully from Lewis rats and induced differentiation along adipogenic and osteogenic lineages in vitro and in vivo. Induction was stimulated by exposing stem cells to lineage-specific induction factors. Adipocyte-inducing media contained dexamethasone, insulin, and isobutyl-methylxanthine. Osteoblast inducing media contained dexamethasone, beta-glycerophosphate, and ascorbic acid. Undifferentiated stem cells were maintained in minimal essential media alpha and fetal bovine serum. At 10 days, cells cultured in adipogenic media differentiated into adipocytes in vitro, as evidenced by positive Oil red O staining of lipid vacuoles. At 21 days, cells cultured in osteogenic media differentiated into osteoblasts in vitro as demonstrated by Alizarin red staining of a calcified extracellular matrix and immunohistochemical staining for osteocalcin. Differentiated cells were seeded at a density of 5 x 106 cells onto 15 x 15-mm polyglycolic acid grafts and implanted subcutaneously into three groups of Lewis rats: Group I contained undifferentiated stem cell grafts, group II contained adipocyte grafts, and group III contained osteoblast grafts. At weeks 4 and 8, in vivo fat formation was demonstrated in group II rats, as confirmed by Oil red O staining. At 8 weeks, group III rats demonstrated in vivo bone formation, as confirmed by the presence of osteocalcin on immunohistochemistry and the characteristic morphology of bone on hematoxylin-eosin staining. Group I rats demonstrated no in vivo bone or fat formation at either time interval. These results demonstrate the ability to isolate pluripotent stem cells from adipose tissue, to induce their differentiation into osteoblasts and adipocytes in vitro, and to form bone and fat subsequently in vivo. This is the first published report of in vivo bone formation from fat-derived stem cells. These cells may eventually serve as a readily available source of autologous stem cells for the engineering of bone and fat.

Once fat was fat and that was that : our changing perspectives on adipose tissue

“…Lee et al 119 was the first to demonstrate that ADSCs could be differentiated into bone-forming osteoblasts and these cells were used to heal critically sized calvarial defects in mice. In a direct comparison during this investigation, ADSCs were found to have the same efficacy as BMSCs.…”

“…Such cells have already been used to correct cranial defects in humans, 119 and preliminary studies in man to rectify cardiovascular 134,135 and soft tissue [136][137][138] defects hold hope for the future use of ADSCs in the treatment of muscle and cartilage defects and heart infarcts. However, before this becomes a reality, there are a number of technical problems that need to be overcome.…”

Bone tissue engineering by using a combination of polymer/Bioglass composites with human adipose-derived stem cells

“…Adipose tissue has recently been demonstrated as a viable source of stem cells that can differentiate along adipogenic, myogenic, chondrogenic, neuronal and osteogenic lineage pathways in vitro (De Ugarte et al 2003;Gabbay et al 2006;Kokai et al 2005;Zuk et al 2002;Zuk et al 2001) and/or in vivo lee (Hicok et al 2004;Lee et al 2003;Lee et al 2010;Parker and Katz 2006;Wosnitza et al 2007). To date, bone marrow has been the traditional source of human multipotent mesenchymal stem cells (MSCs) for skeletal tissue engineering but adipose tissue appears to offer an alternative, more readily available and highly accessible stem cell source (Mehrkens et al 2012;Sterodimas et al 2009).…”

Regenerative Medicine for Tendon Regeneration and Repair: The Role of Bioscaffolds and Mechanical Loading

“…Studies have shown that raw adipose tissue contains a population of adult stem cells that can differentiate into bone, fat, cartilage, or muscle in vitro. ( Lee RH et al 2004) (Zuk PA et al 2001) (Lee JA et al 2003) These adipose-derived stem cells are easily accessible and unlike marrow are available in large quantities with acceptable morbidity and discomfort associated with their harvest. The autologous nature of these stem cells together with their putative multipotentiality and ease of procurement may make these cells an excellent choice for many future tendonengineering strategies and cell-based therapies.…”