The Adipose-derived Stem Cell: Looking Back and Looking Ahead- Dr. Patricia Zuk
The initial results published in Tissue Engineering seemed to support this theory. To confirm this theory, our team undertook a more extensive molecular and biochemical analysis of the ASC (i.e., the PLA cell) in our 2002 MBoC article (Zuk et al., 2002). This article not only confirmed our earlier work that the ASC is capable of differentiating into multiple mesodermal cell types—adipogenic, chondrogenic, osteogenic, and myogenic (Zuk et al., 2001), but utilized additional approaches such as the expression of multiple lineage–specific genes and functional biochemical assays to confirm this property. Combining these approaches, the data of our MBoC article appeared to fulfill one important requirement of a stem cell: differentiation capacity. However, the MBoC article also fulfilled another important requirement specific to adult stem cells, that of clonogenicity. One of the most obvious hurdles for adult stem cell identification is the heterogeneity of their origin tissue. Because of this, the observed multilineage differentiation by ASCs may simply be due to the presence of multiple precursor populations, each completing their development. One way to circumvent this would be the isolation of a stem cell, combined with proof of its multipotency.
THE WIDE, WIDE WORLD OF ADRCs
THE FUTURE OF ASCs
Only time will tell.
Editors note: The team around Dr.Zuk was instrumental in describing Fat cells , which obviously was very important in spreading the news amongst academia. As Dr. Zuk describes at the end of the paper, stem cells now have been found in all kinds of tissue types- understanding why that is, we owe to Dr. Arnold Caplan, the first scientist to describe the MSC (not its discoverer). Of course- Caplan and his papers are an impotant part of this website too. But first- Dr. Zuk´s monumental paper from 2002 is a free paper available on PubMed- for that reason I provide an overview of all six available free papers below.
Manual isolation of adipose-derived stem cells from human lipoaspirates.
J Vis Exp. 2013;(79):e50585
Authors: Zhu M, Heydarkhan-Hagvall S, Hedrick M, Benhaim P, Zuk P
In 2001, researchers at the University of California, Los Angeles, described the isolation of a new population of adult stem cells from liposuctioned adipose tissue that they initially termed Processed Lipoaspirate Cells or PLA cells. Since then, these stem cells have been renamed as Adipose-derived Stem Cells or ASCs and have gone on to become one of the most popular adult stem cells populations in the fields of stem cell research and regenerative medicine. Thousands of articles now describe the use of ASCs in a variety of regenerative animal models, including bone regeneration, peripheral nerve repair and cardiovascular engineering. Recent articles have begun to describe the myriad of uses for ASCs in the clinic. The protocol shown in this article outlines the basic procedure for manually and enzymatically isolating ASCs from large amounts of lipoaspirates obtained from cosmetic procedures. This protocol can easily be scaled up or down to accommodate the volume of lipoaspirate and can be adapted to isolate ASCs from fat tissue obtained through abdominoplasties and other similar procedures.
PMID: 24121366 [PubMed - indexed for MEDLINE]
Nuclear fusion-independent smooth muscle differentiation of human adipose-derived stem cells induced by a smooth muscle environment.
Stem Cells. 2012 Mar;30(3):481-90
Authors: Zhang R, Jack GS, Rao N, Zuk P, Ignarro LJ, Wu B, Rodríguez LV
Human adipose-derived stem cells hASC have been isolated and were shown to have multilineage differentiation capacity. Although both plasticity and cell fusion have been suggested as mechanisms for cell differentiation in vivo, the effect of the local in vivo environment on the differentiation of adipose-derived stem cells has not been evaluated. We previously reported the in vitro capacity of smooth muscle differentiation of these cells. In this study, we evaluate the effect of an in vivo smooth muscle environment in the differentiation of hASC. We studied this by two experimental designs: (a) in vivo evaluation of smooth muscle differentiation of hASC injected into a smooth muscle environment and (b) in vitro evaluation of smooth muscle differentiation capacity of hASC exposed to bladder smooth muscle cells. Our results indicate a time-dependent differentiation of hASC into mature smooth muscle cells when these cells are injected into the smooth musculature of the urinary bladder. Similar findings were seen when the cells were cocultured in vitro with primary bladder smooth muscle cells. Chromosomal analysis demonstrated that microenvironment cues rather than nuclear fusion are responsible for this differentiation. We conclude that cell plasticity is present in hASCs, and their differentiation is accomplished in the absence of nuclear fusion.
PMID: 22213158 [PubMed - indexed for MEDLINE]
Osteoblast interactions within a biomimetic apatite microenvironment.
Ann Biomed Eng. 2011 Apr;39(4):1186-200
Authors: Tsang EJ, Arakawa CK, Zuk PA, Wu BM
Numerous reports have shown that accelerated apatites can mediate osteoblastic differentiation in vitro and bone formation in vivo. However, how cells interact within the apatite microenvironment remains largely unclear, despite the vast literature available today. In response, this study evaluates the in vitro interactions of a well-characterized osteoblast cell line (MC3T3-E1) with the apatite microenvironment. Specifically, cell attachment, spreading, and viability were evaluated in the presence and absence of serum proteins. Proteins were found to be critical in the mediation of cell-apatite interactions, as adherence of MC3T3-E1 cells to apatite surfaces without protein coatings resulted in significant levels of cell death within 24 h in serum-free media. In the absence of protein-apatite interaction, cell viability could be "rescued" upon treatment of MC3T3-E1 cells with inhibitors to phosphate (PO(4) (3-)) transport, suggesting that PO(4) (3-) uptake may play a role in viability. In contrast, rescue was not observed upon treatment with calcium (Ca(2+)) channel inhibitors. Interestingly, a rapid "pull-down" of extracellular Ca(2+) and PO(4) (3-) ions onto the apatite surface could be measured upon the incubation of apatites with α-MEM, suggesting that cells may be subject to changing levels of Ca(2+) and PO(4) (3-) within their microenvironment. Therefore, the biomimetic apatite surface may significantly alter the microenvironment of adherent osteoblasts and, as such, be capable of affecting both cell survival and differentiation.
PMID: 21234689 [PubMed - indexed for MEDLINE]
The adipose-derived stem cell: looking back and looking ahead.
Mol Biol Cell. 2010 Jun 1;21(11):1783-7
Authors: Zuk PA
In 2002, researchers at UCLA published a manuscript in Molecular Biology of the Cell describing a novel adult stem cell population isolated from adipose tissue-the adipose-derived stem cell (ASC). Since that time, the ASC has gone on to be one of the most popular adult stem cell populations currently being used in the stem cell field. With multilineage mesodermal potential and possible ectodermal and endodermal potentials also, the ASC could conceivably be an alternate to pluripotent ES cells in both the lab and in the clinic. In this retrospective article, a historical perspective on the ASC is given together with exciting new applications for the stem cell being considered today.
PMID: 20375149 [PubMed - indexed for MEDLINE]
Bone induction by BMP-2 transduced stem cells derived from human fat.
J Orthop Res. 2003 Jul;21(4):622-9
Authors: Dragoo JL, Choi JY, Lieberman JR, Huang J, Zuk PA, Zhang J, Hedrick MH, Benhaim P
PURPOSE: We have isolated pluripotent mesenchymal progenitor cells in large numbers from liposuction aspirates (processed lipoaspirate cells or PLAs). This study examines the osteogenic potential of PLAs and bone marrow aspirate cells (BMAs), when exposed to either recombinant human bone morphogenetic protein (BMP)-2 (rh-BMP-2) or adenovirus containing BMP-2 cDNA (Ad-BMP-2).
METHODS: Liposuction aspirates underwent proteolytic digestion to obtain PLAs. After exposure to exogenous rh-BMP-2 or Ad-BMP-2 for four or seven days, PLAs and BMAs were assessed by histochemistry, spectrophotometry and RT-PCR. Western blotting and ELISA confirmed BMP gene transduction. Results were compared to osteoblasts and cells in osteogenic media only. PLA-Ad-BMP-2 cells were seeded on matrices and implanted in the hind limbs of SCID mice.
RESULTS: Analysis of quantified bone precursor assays including extracellular ALP histomorphometry, intracellular ALP spectrophotometry, and calcified extracellular matrix (von Kossa) histomorphometry revealed that PLAs treated with exogenous rh-BMP-2 or transduced with a BMP-2 containing adenovirus (PLA-Ad-BMP-2) produced more bone precursors than osteoblasts (p=0.001). PLAs treated with exogenous rh-BMP-2 or PLA-Ad-BMP-2 also produced more bone precursors than BMAs (p=0.001), except for day 7 ALP histomorphometry (p=0.343). ELISA confirmed successful BMP-2 production by both progenitor cell groups transduced with Ad-BMP-2. H&E sections from collagen I matrices seeded with PLA-Ad-BMP-2 cells confirmed bone formation at six weeks.
CONCLUSIONS: Liposuction aspirates contain PLAs that can be transfected with the BMP-2 gene, with rapid induction into the osteoblast phenotype at a rate comparable to rh-BMP-2 and osteoblast groups. Transduced PLAs produce more bone precursors with faster onset of calcified extracellular matrix than transduced BMAs. PLAs may be an ideal source of mesenchyme-lineage stem cells for gene therapy and tissue engineering.
PMID: 12798061 [PubMed - indexed for MEDLINE]
Human adipose tissue is a source of multipotent stem cells.
Mol Biol Cell. 2002 Dec;13(12):4279-95
Authors: Zuk PA, Zhu M, Ashjian P, De Ugarte DA, Huang JI, Mizuno H, Alfonso ZC, Fraser JK, Benhaim P, Hedrick MH
Much of the work conducted on adult stem cells has focused on mesenchymal stem cells (MSCs) found within the bone marrow stroma. Adipose tissue, like bone marrow, is derived from the embryonic mesenchyme and contains a stroma that is easily isolated. Preliminary studies have recently identified a putative stem cell population within the adipose stromal compartment. This cell population, termed processed lipoaspirate (PLA) cells, can be isolated from human lipoaspirates and, like MSCs, differentiate toward the osteogenic, adipogenic, myogenic, and chondrogenic lineages. To confirm whether adipose tissue contains stem cells, the PLA population and multiple clonal isolates were analyzed using several molecular and biochemical approaches. PLA cells expressed multiple CD marker antigens similar to those observed on MSCs. Mesodermal lineage induction of PLA cells and clones resulted in the expression of multiple lineage-specific genes and proteins. Furthermore, biochemical analysis also confirmed lineage-specific activity. In addition to mesodermal capacity, PLA cells and clones differentiated into putative neurogenic cells, exhibiting a neuronal-like morphology and expressing several proteins consistent with the neuronal phenotype. Finally, PLA cells exhibited unique characteristics distinct from those seen in MSCs, including differences in CD marker profile and gene expression.
PMID: 12475952 [PubMed - indexed for MEDLINE]