Migration Of Preadipocytes Research Articles

Adipose tissue reconstruction facilitated with low immunogenicity decellularized adipose tissue scaffolds.

There is currently an urgent need to develop engineered scaffolds to support new adipose tissue formation and facilitate long-term maintenance of function and defect repair to further generate prospective bioactive filler materials capable of fulfilling surgical needs. Herein, adipose regeneration methods were optimized and decellularized adipose tissue (DAT) scaffolds with good biocompatibility were fabricated. Adipose-like tissues were reconstructed using the DAT and 3T3-L1 preadipocytes, which have certain differentiation potential, and the regenerative effects of the engineered adipose tissuesin vitroandin vivowere explored. The method improved the efficiency of adipose removal from tissues, and significantly shortened the time for degreasing. Thus, the DAT not only provided a suitable space for cell growth but also promoted the proliferation, migration, and differentiation of preadipocytes within it. Following implantation of the constructed adipose tissuesin vivo, the DAT showed gradual degradation and integration with surrounding tissues, accompanied by the generation of new adipose tissue analogs. Overall, the combination of adipose-derived extracellular matrix and preadipocytes for adipose tissue reconstruction will be of benefit in the artificial construction of biomimetic implant structures for adipose tissue reconstruction, providing a practical guideline for the initial integration of adipose tissue engineering into clinical medicine.

The myokine CCL5 recruits subcutaneous preadipocytes and promotes intramuscular fat deposition in obese mice.

Intramuscular fat (IMF) refers to the lipid stored in skeletal muscle tissue. The number and size of intramuscular adipocytes are the primary factors that regulate IMF content. Intramuscular adipocytes can be derived from either in situ or ectopic migration. In this study, it was discovered that the regulation of IMF levels is achieved through the chemokine (C-C motif) ligand 5 (CCL5)/chemokine (C-C motif) receptor 5 (CCR5) pathway by modulating adipocyte migration. In coculture experiments, C2C12 myotubes were more effective in promoting the migration of 3T3-L1 preadipocytes than C2C12 myoblasts, along with increasing CCL5. Correspondingly, overexpressing the CCR5, one of the receptors of CCL5, in 3T3-L1 preadipocytes facilitated their migration. Conversely, the application of the CCL5/CCR5 inhibitor, MARAVIROC (MVC), reduced this migration. In vivo, transplanted experiments of subcutaneous adipose tissue (SCAT) from transgenic mice expressing green fluorescent protein (GFP) provided evidence that injecting recombinant CCL5 (rCCL5) into skeletal muscle promotes the migration of subcutaneous adipocytes to the skeletal muscle. The level of CCL5 in skeletal muscle increased with obesity. Blocking the CCL5/CCR5 axis by MVC inhibited IMF deposition, whereas elevated skeletal muscle CCL5 promoted IMF deposition in obese mice. These results establish a link between the IMF and the CCL5/CCR5 pathway, which could have a potential application for modulating IMF through adipocyte migration.NEW & NOTEWORTHY C2C12 myotubes attract 3T3-L1 preadipocyte migration regulated by the chemokine (C-C motif) ligand 5 (CCL5)/ chemokine (C-C motif) receptor 5 (CCR5) axis. High levels of skeletal muscle-specific CCL5 promote the migration of subcutaneous adipocytes to skeletal muscle and induce the intramuscular fat (IMF) content.

Kindlin-2 regulates the differentiation of 3T3-L1 preadipocytes: implications for wound healing.

BackgroundAdipose tissue has been proven to play a crucial role in wound healing, while kindlin-2, an integrin-associated protein, has been shown to regulate cell adhesion, migration, and differentiation. This study aimed to explore its involvement in the cell differentiation of 3T3-L1 preadipocytes and its role in wound healing.MethodsCell adhesion, Cell Counting Kit-8 (CCK-8), Transwell, and in vitro wound healing assays, along with adipogenic and osteogenic differentiation induction were performed in 3T3-L1 preadipocytes in which kindlin-2 was knocked down or overexpressed. In vivo, kindlin-2 (+/−) transgenic mice were constructed, and wound healing was analyzed by immunohistochemistry (IHC) in a mouse dorsal wound model. Real-time polymerase chain reaction (RT-PCR) and western blotting were performed to analyze the expression of adipokines and adipogenic markers in mouse wound tissues. Adipogenic differentiation induction of adipose tissue stromal vascular fraction (SVF) were performed, and the expression of adipogenic markers in SVF was detected by western blotting. The target signaling pathway highly related to adipogenic differentiation was explored by computational biology and verified by western blotting.ResultsKnockdown of kindlin-2 was found to inhibit the adhesion, migration, and adipogenic differentiation of 3T3-L1 preadipocytes while promoting their osteogenic differentiation. In contrast, kindlin-2 overexpression resulted in increased adhesion, migration, and adipogenic differentiation of 3T3-L1 preadipocytes while reducing osteogenic differentiation. In vivo, downregulation of kindlin-2 inhibited adipogenesis in kindlin-2 transgenic mice, resulting in delayed wound healing by inhibiting inflammation, angiogenesis, collagen remodeling, and wound contraction. Mechanistically, we found that kindlin-2 could regulate adipogenic differentiation through PI3K/AKT/mTOR signaling pathway.ConclusionsOur study revealed the essential role that kindlin-2 has in the differentiation and wound healing of 3T3-L1 preadipocytes, which offers a theoretical basis for further research and a novel strategy for wound healing.

ACTIVATED INTESTINAL MUSCLE CELLS PROMOTE PREADIPOCYTE MIGRATION: A NOVEL MECHANISM OF CREEPING FAT FORMATION IN CROHN’S DISEASE

Abstract Background and Aims Creeping fat, the wrapping of mesenteric fat around the bowel wall, is a typical feature of Crohn’s disease, and is associated with stricture formation and bowel obstruction. How creeping fat forms is unknown, and we interrogated potential mechanisms using novel intestinal tissue and cell interaction systems. Methods Tissues from normal, ulcerative colitis, non-strictured and strictured Crohn’s disease intestinal specimens were obtained. Fresh and decellularized tissue, mesenteric fat explants, primary human adipocytes, pre-adipocytes, muscularis propria cells, and native extracellular matrix were used in multiple ex vivo and in vitro systems involving cell growth, differentiation and migration, proteomics, and integrin expression. Results Crohn’s disease muscularis propria cells produced an extracellular matrix scaffold which is in direct spatial and functional contact with the immediately overlaid creeping fat. The scaffold contained multiple proteins, but only fibronectin production was singularly upregulated by TGF-b1. The muscle cell-derived matrix triggered migration of pre-adipocytes out of mesenteric fat, fibronectin being the dominant factor responsible for their migration. Blockade of α5β1 on the pre-adipocyte surface inhibited their migration out of mesenteric fat and on 3D decellularized intestinal tissue extracellular matrix. Conclusion Crohn’s disease creeping fat appears to result from the migration of pre-adipocytes out of mesenteric fat and differentiation into adipocytes in response to an increased production of fibronectin by activated muscularis propria cells. These new mechanistic insights may lead to novel approaches for prevention of creeping fat-associated stricture formation.

Activated intestinal muscle cells promote preadipocyte migration: a novel mechanism for creeping fat formation in Crohn’s disease

ObjectiveCreeping fat, the wrapping of mesenteric fat around the bowel wall, is a typical feature of Crohn’s disease, and is associated with stricture formation and bowel obstruction. How creeping fat...

Silibinin-induced autophagy mediated by PPARα-sirt1-AMPK pathway participated in the regulation of type I collagen-enhanced migration in murine 3T3-L1 preadipocytes.

Preadipocyte migration is a fundamental and important process for the development of tissue organization, especially in the development of primitive adipose tissue and adipocyte tissue wound healing. However, excessive migration may result in abnormal development and fibrosis-related diseases such as hypertrophic scar. We previously reported that type I collagen (collagen I) enhanced migration of 3T3-L1 preadipocytes via phosphorylation and/or acetylation of NF-κB p65, and the enhanced cell migration is repressed by silibinin treatment through sirt1. It is known that sirt1 has an ability to deacetylate acetylated NF-κB p65, but little is known about the effect of sirt1 on phosphorylated NF-κB p65. This study aims to examine the potential effect of sirt1 on the regulation of phosphorylated NF-κB p65 and the underlying mechanism. Autophagy is involved in many physiological and pathological processes, including regulation of cell migration as well as in cellular homeostasis. The present study demonstrates that silibinin induces autophagy in a dose-dependent manner in 3T3-L1 cells. Autophagy is under the regulation of sirt1/AMPK pathway, and inhibits collagen I-enhanced migration of 3T3-L1 cells through negative regulation of NF-κB p65 phosphorylation but not acetylation. The expression of peroxisome proliferator-activated receptor α (PPARα) is up-regulated with silibinin accompanying up-regulation of autophagy through activating sirt1 in 3T3-L1 cells. Taken together, these findings indicate that silibinin-induced autophagy is mediated by up-regulation of PPARα-sirt1-AMPK, contributing to repression of type I collagen-enhanced migration in murine 3T3-L1 preadipocytes through down-regulation of phosphorylated NF-κB p65.

Enhanced migration of murine fibroblast-like 3T3-L1preadipocytes on type I collagen-coated dish is reversed by silibinin treatment.

Migration of fibroblast-like preadipocytes is important for the development of adipose tissue, whereas excessive migration is often responsible for impaired adipose tissue related with obesity and fibrotic diseases. Type I collagen (collagen I) is the most abundant component of extracellular matrix and has been shown to regulate fibroblast migration in vitro, but its role in adipose tissue is not known. Silibinin is a bioactive natural flavonoid with antioxidant and antimetastasis activities. In this study, we found that type I collagen coating promoted the proliferation and migration of murine 3T3-L1 preadipocytes in a dose-dependent manner, implying that collagen I could be an extracellular signal. Regarding the mechanisms of collagen I-stimulated 3T3-L1 migration, we found that NF-κB p65 is activated, including the increased nuclear translocation of NF-κB p65 as well as the upregulation of NF-κB p65 phosphorylation and acetylation, accompanied by the increased expressions of proinflammatory factors and the generation of reactive oxygen species (ROS). Reduction of collagen I-enhanced migration of cells by treatment with silibinin was associated with suppression of NF-κB p65 activity and ROS generation, and negatively correlated with the increasing sirt1 expression. Taken together, the enhanced migration of 3T3-L1 cells induced on collagen I-coated dish is mediated by the activation of NF-κB p65 function and ROS generation that can be alleviated with silibinin by upregulation of sirt1, leading to the repression of NF-κB p65 function and ROS generation.

Asymmetry in traction forces produced by migrating preadipocytes is bounded to 33%

Wound healing by gap closure is accomplished by the migratory cells within tissues. In fat tissue, the preadipocytes, stem cells committed to the adipose (fat) lineage, typically migrate into the wound area, and then differentiate into mature adipocytes to facilitate tissue repair and regeneration. While cell migration has previously been characterized, typically for fibroblasts, little is known about the dynamic, mechanical interactions of migrating cells with their microenvironment; cells crawl on a two-dimensional (2D) substrate by attaching and applying forces that allow them to extend leading edges and retract their rear. Moreover, preadipocytes, the highly migratory precursors of fat cells, have not been studied from this aspect. Here, we have evaluated the migration of preadipocytes, through their speed and directionality as well as the magnitude of the lateral forces applied during their migration on a 2D gel with Young's modulus of 2.44 kPa. We have found that the preadipocytes migrate non-directionally in the absence of chemoattractant, at an average rate of 0.27 µm/min, similar to fibroblasts. The preadipocytes exhibited a wide range of total traction forces (100–800 nN), and migrated along the long axis of their elongated morphology. Interestingly, we have observed an asymmetry in the location of force application between the lead and rear of the cells that was bounded in magnitude, where cells applied only up to 33% more force on either side; cell sides were defined relative to the minor axis of a bounding ellipse. These quantitative mechanobiological aspects of natural preadipocyte migration may shed light on the wound healing processes occurring in adipose tissue.

Role of adiponectin in adipose tissue wound healing.

The purpose of this study was to investigate the mechanism behind adipose tissue wound healing (ATWH). The preadipocyte cell line 3T3-L1 was cultured and expression of adiponectin receptors (AdipoR1/2) was detected by immunohistochemistry and reverse transcription polymerase chain reaction. The concentration of adiponectin secreted at different cell densities was measured by enzyme-linked immunosorbent assay, while preadipocyte proliferation and migration were determined in vitro by MTT and wound closure assays. AdipoR1/2 were found to be expressed in 3T3-L1 preadipocytes. There were no statistically significant differences in the concentrations of adiponectin secreted by cell solutions of different densities (P > 0.05). In addition, adiponectin was seen to promote the growth and migration of preadipocytes. In conclusion, adiponectin may regulate ATWH by promoting preadipocyte proliferation and migration, and its systemic and/or local application is proposed as a promising therapeutic approach for the treatment of wounds incurred as a result of surgery.

Cytohesin 2/ARF6 regulates preadipocyte migration through the activation of ERK1/2

Preadipocyte migration is vital for the development of adipose tissue, which plays a crucial role in lipid metabolism. ADP-ribosylation factor 6 (ARF6) small GTPase, which regulates membrane trafficking, is activated by GTP-exchange factors (GEFs) such as cytohesin 2. Cytohesin 2 and ARF6 have previously been implicated in the regulation of 3T3-L1 preadipocyte migration. We investigated here the molecular mechanism underlying the cytohesin 2 and ARF6 mediated regulation of preadipocyte migration. Preadipocyte migration and the activation of ARF6 and ERK1/2 were studied by using a number of approaches, including pharmacological inhibitors, siRNA and the inhibitory peptides. The siRNA mediated down regulation of ARF6 and cytohesin 2 expression confirmed the requirement of both for migration of preadipocytes. Phosphatidylinositol 3-kinase (PI3K) and PI 4,5-bisphosphate (PIP2) have also found to be essential for the cytohesin 2/ARF6 induced preadipocyte migration. Pharmacological inhibition of the activation of ARF6, ERK1/2 or dynamin led to significant reduction in migration of 3T3-L1 preadipocytes. Furthermore, our study revealed the activation of ARF6 and ERK1/2 during migration of preadipocytes. In the migrating preadipocytes, ARF6 activation was inhibited with SecinH3 (cytohesin inhibitor) and LY294002 (PI3K inhibitor) whereas the ERK1/2 phosphorylation was inhibited with SecinH3, LY294002, PBP10 (a PIP2 sequester peptide) and PD98059 (MAPKK inhibitor). However, dynosore (dynamin inhibitor) had inhibited neither ARF6 activation nor ERK1/2 phosphorylation during preadipocyte migration. These results together suggest that cytohesin 2 activates ARF6 in a PI3K dependent manner and then the active ARF6 causes phosphorylation of ERK1/2 during preadipocyte migration.

Selenium improves stem cell potency by stimulating the proliferation and active migration of 3T3-L1 preadipocytes

Selenium is a trace nutrient element that protects cells against oxidative damage. In this study, the potential of selenium to improve stem cell potency through active proliferation and migration of 3T3-L1 preadipocytes was investigated, together with the underlying molecular mechanisms. The results indicated that selenium applied for 24 h stimulated cell proliferation up to 20% compared to untreated control cells. Selenium induced the expression of cyclin-dependent kinase (CDK) 1 and CDK2, which are known to regulate G2/M progression, and significantly downregulated the CDK inhibitors p21 and p27. Selenium also activated the expression of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway, as well as extracellular signal-regulated kinase (ERK). Although LY294002, an inhibitor of PI3K, significantly inhibited the selenium-induced cell proliferation of the 3T3-L1 preadipocytes, PD98059, an inhibitor of ERK, did not affect selenium-induced active proliferation. These results clearly indicate that selenium stimulated cell proliferation through cell cycle progression and PI3K/Akt activation, but not through ERK activation. Furthermore, selenium increased 3T3-L1 cell migration, which was associated with the induction of matrix metalloproteinase (MMP)-2 and MMP-9. Taken together, the current findings suggest that selenium can stimulate stem cell potency by increasing the proliferation and active migration of 3T3-L1 cells.

Curcumin stimulates proliferation, stemness acting signals and migration of 3T3-L1 preadipocytes

In the present study, the potential of curcumin to stimulate proliferation, stemness acting signals and migration of 3T3-L1 preadipocytes and the associated molecular mechanisms were investigated. Low concentrations of curcumin stimulated cell proliferation, whereas high concentrations were cytotoxic to 3T3-L1 cells. In particular, application of 0.02 µM of curcumin for 24 h resulted in significantly increased cell proliferation and was determined to be the optimal treatment for this study. In a colony-forming cell assay, cells treated with 0.02 µM of curcumin showed an approximately 1.5-fold increase in colony formation. Curcumin treatment up-regulated the proliferation-related marker proteins coupled with increased cell growth, telomerase activity and overexpression of stemness acting signals, which was associated with activation of the phosphoinositide 3-kinase (PI3K) pathway. In addition, curcumin significantly inactivated p38 mitogen-activated protein kinases (MAPK) and stress-activated protein kinase/c-Jun N-terminal kinases (SARK/JNK), coupled with inhibition of p53 and p21 tumor suppressor gene products. In addition, curcumin significantly increased cell migration through activation of migration-associated transcription factors. Therefore, these results clearly show that activation of cell proliferation by curcumin is associated with improved stem cell potency in 3T3-L1 preadipocytes.

Cytohesin-2/ARNO, through Its Interaction with Focal Adhesion Adaptor Protein Paxillin, Regulates Preadipocyte Migration via the Downstream Activation of Arf6

The formation of primitive adipose tissue is the initial process in adipose tissue development followed by the migration of preadipocytes into adipocyte clusters. Comparatively little is known about the molecular mechanism controlling preadipocyte migration. Here, we show that cytohesin-2, the guanine-nucleotide exchange factor for the Arf family GTP-binding proteins, regulates migration of mouse preadipocyte 3T3-L1 cells through Arf6. SecinH3, a specific inhibitor of the cytohesin family, markedly inhibits migration of 3T3-L1 cells. 3T3-L1 cells express cytohesin-2 and cytohesin-3, and knockdown of cytohesin-2 with its small interfering RNA effectively decreases cell migration. Cytohesin-2 preferentially acts upstream of Arf6 in this signaling pathway. Furthermore, we find that the focal adhesion protein paxillin forms a complex with cytohesin-2. Paxillin colocalizes with cytohesin-2 at the leading edges of migrating cells. This interaction is mediated by the LIM2 domain of paxillin and the isolated polybasic region of cytohesin-2. Importantly, migration is inhibited by expression of the constructs containing these regions. These results suggest that cytohesin-2, through a previously unexplored complex formation with paxillin, regulates preadipocyte migration and that paxillin plays a previously unknown role as a scaffold protein of Arf guanine-nucleotide exchange factor.

Melanin-concentrating hormone facilitates migration of preadipocytes

Adipose tissue develops from differentiating preadipocytes that expand and migrate. 3T3-L1 preadipocytes respond to melanin-concentrating hormone (MCH) by increasing leptin production. Here, we investigate whether MCH elicits remodeling of the actin cytoskeleton and whether this translates into altered migratory capacity of these cells. Incubation with MCH resulted in a loss of actin stress fibers accompanied by a change in morphology from a stretched-out fibroblast to a rounded cell. PMC-3881-PI, a MCH receptor 1 antagonist blocked the effect, confirming this receptor is solely responsible for MCH-mediated actin rearrangements. Both a pharmacological activator and inhibitor of phospholipase C were used to demonstrate this molecule's importance to the signaling pathway. Finally, MCH was shown to facilitate preadipocyte migration into a scratch wound, revealing a previously unknown role for MCH in the regulation of cellular migration. We conclude that MCH could influence the expansion of adipose tissue through its ability to enhance preadipocyte migration.

Fat-Storing Multilocular Cells Expressing CCR5 Increase in the Thymus with Advancing Age: Potential Role for CCR5 Ligands on the Differentiation and Migration of Preadipocytes

Age-associated thymic involution is characterized by decreased thymopoiesis, adipocyte deposition and changes in the expression of various thymic microenvironmental factors. In this work, we characterized the distribution of fat-storing cells within the aging thymus. We found an increase of unilocular adipocytes, ERTR7(+) and CCR5(+ )fat-storing multilocular cells in the thymic septa and parenchymal regions, thus suggesting that mesenchymal cells could be immigrating and differentiating in the aging thymus. We verified that the expression of CCR5 and its ligands, CCL3, CCL4 and CCL5, were increased in the thymus with age. Hypothesizing that the increased expression of chemokines and the CCR5 receptor may play a role in adipocyte recruitment and/or differentiation within the aging thymus, we examined the potential role for CCR5 signaling on adipocyte physiology using 3T3-L1 pre-adipocyte cell line. Increased expression of the adipocyte differentiation markers, PPARgamma2 and aP2 in 3T3-L1 cells was observed under treatment with CCR5 ligands. Moreover, 3T3-L1 cells demonstrated an ability to migrate in vitro in response to CCR5 ligands. We believe that the increased presence of fat-storing cells expressing CCR5 within the aging thymus strongly suggests that these cells may be an active component of the thymic stromal cell compartment in the physiology of thymic aging. Moreover, we found that adipocyte differentiation appear to be influenced by the proinflammatory chemokines, CCL3, CCL4 and CCL5.

Cell migration of preadipocytes on the isolated mouse mesenterium

Cell migration of preadipocytes on the isolated mouse mesenterium

Extracellular ATP-induced cell migration of preadipocytes: chemotaxis and chemokinesis

Extracellular ATP-induced cell migration of preadipocytes: chemotaxis and chemokinesis

Inhibition of adipogenesis by RGD-dependent disintegrin

Adipogenesis plays a central role in obesity development. The processes of adipogenesis include migration, adhesion, proliferation and survival of preadipocytes and differentiation to mature adipocytes. Many of these biological functions are related to integrins. Here, we found that snake venom-derived arginine–glycine–aspartic acid (RGD)-containing disintegrin inhibited adipogenesis. Rhodostomin but not rhodostomin RGD mutants (RGE-Rn and AKGDWN-Rn) caused the detachment of primary cultured preadipocyte. Furthermore, rhodostomin also inhibited focal adhesion of preadipocyte, including the inhibition of the expression of focal adhesion kinase (FAK) and FAK phosphorylation, assembly of vinculin and reorganization of actin cytoskeleton. Cell viability of preadipocytes was decreased after rhodostomin treatment in a concentration-dependent manner. The results of flow cytometric analysis showed that rhodostomin induced cell apoptosis. In addition, chromatin condensation was observed in DAPI staining. The increase of Bax expression and activation of capsase-3 was detected following rhodostomin treatment. Addition of dexamethasone, IBMX and insulin induced differentiation of preadipocytes into mature adipocytes and treatment of cells with rhodostomin during the initial 3 days showed less mature adipocytes following 9–10 days of differentiating period. The triglyceride content and gene expression of peroxisome proliferators-activated receptor gamma (PPARγ) and leptin also decreased in response to the treatment of rhodostomin. These results suggest that disintegrin inhibits processes of adipogenesis and may be developed to treat obesity.

Photocured, styrenated gelatin-based microspheres for de novo adipogenesis through corelease of basic fibroblast growth factor, insulin, and insulin-like growth factor I.

De novo adipose tissue formation appears to proceed via two different biological events: neovascularization and spontaneous accumulation of preadipocytes and subsequent differentiation to mature adipocytes. In this article, we perform accelerated de novo adipose tissue engineering using photocured, styrenated, gelatin-based microspheres (SGMs) with different drug release rates of immobilized angiogenic and adipogenic factors. The concept of this system is to induce neovascularization and migration of endogenous preadipocytes by the rapid delivery of the angiogenic factor basic fibroblast growth factor (bFGF), followed by the proliferation and differentiation of preadipocytes into adipocytes by the prolonged delivery of the adipogenic factors, insulin and insulin-like growth factor I (IGF-I). Bioactive substance-immobilized SGMs with different drug release rates were prepared with different gelatin concentrations. An in vitro study showed the prolonged release of an immobilized model protein and the dependence of drug release rate on gelatin concentration. After the subcutaneous injections of SGMs immobilized with these bioactive substances in different combinations, the formation of masses or clusters of adipocytes was observed in rats. Triglyceride content in the injection site for the group that received bFGF-, insulin-, and IGF-I-immobilized SGMs was significantly higher than that for the group that received insulin- and IGF-I-immobilized SGMs 4 weeks after the injection of microspheres. These results suggest that the system developed here is effective for the de novo formation of adipose tissue as it enables the induction of the two-step biological reaction by single injection.

Autocrine regulation of human preadipocyte migration by plasminogen activator inhibitor-1.

One of the initial stages of adipogenesis is migration of preadipocytes of mesenchymal origin into cell clusters to form primitive fat organs. The serine protease inhibitor plasminogen activator inhibitor-1 (PAI-1) is synthesized and released from human adipose tissue ex vivo and regulates smooth muscle and endothelial cell migration in vitro, but its role in adipose tissue is not known. We investigated the role of PAI-1 in cultures of human preadipocytes from men and women of various ages and body mass indexes. Human preadipocytes expressed the messenger ribonucleic acid for PAI-1 and released significant quantities of PAI-1 protein into the medium. As PAI-1 regulates motility through the interaction of vitronectin with its receptor, the integrin alphaVbeta3, we identified this receptor in human preadipocytes. Flow cytometric analysis indicated that human preadipocytes express the vitronectin receptor alphaVbeta3 in a similar pattern as human umbilical vein endothelial cells. Functional studies indicated that active, but not latent, PAI-1 inhibited preadipocyte attachment to vitronectin with an IC(50) of 13.3 nmol/L, and preincubation of vitronectin-coated Transwells with active PAI-1 prevented preadipocyte migration. Vitronectin was identified in homogenates of the stromal-vascular fraction of human adipose tissue, but was absent from human adipocytes and cultured preadipocytes. These data indicate that human preadipocyte migration is regulated through the endogenous expression of PAI-1 and alphaVbeta3 integrin, a novel autocrine mechanism for potentially regulating cell cluster formation in adipogenesis.