Pathways commonly dysregulated in mouse and human obese adipose tissue: FAT/CD36 modulates differentiation and lipogenesis.

Obesity is linked to adipose tissue hypertrophy (increased adipocyte cell size) and hyperplasia (increased cell number). Comparative analyses of gene datasets allowed us to identify 1426 genes which may represent common adipose phenotype in humans and mice. Among them we identified several adipocyte-specific genes dysregulated in obese adipose tissue, involved in either fatty acid storage (acyl CoA synthase ACSL1, hormone-sensitive lipase LIPE, aquaporin 7 AQP7, perilipin PLIN) or cell adhesion (fibronectin FN1, collagens COL1A1, COL1A3, metalloprotein MMP9, or both (scavenger receptor FAT/CD36). Using real-time analysis of cell surface occupancy on xCELLigence system we developed a new method to study lipid uptake and differentiation of mouse 3T3L1 fibroblasts and human adipose stem cells. Both processes are regulated by insulin and fatty acids such as oleic acid. We showed that fatty acid addition to culture media increased the differentiation rate and was required for full differentiation into unilocular adipocytes. Significant activation of lipogenesis, i.e. lipid accumulation, by either insulin or oleic acid was monitored in times ranging from 1 to 24 h, depending on differentiation state, whereas significant effects on adipogenesis, i.e., surperimposed lipid accumulation and gene transcriptional regulations were measured after 3 to 4 d. Combination of selected times for analysis of lipid contents, cell counts, size fractionations, and gene transcriptional regulations showed that FAT/CD36 specific inhibitor AP5258 significantly increased cell survival of oleic acid-treated mouse and human adipocytes, and partially restored the transcriptional response to oleic acid in the presence of insulin through JNK pathway. Taken together, these data open new perspectives to study the molecular mechanisms commonly dysregulated in mouse and human obesity at the level of lipogenesis linked to hypertrophy and adipogenesis linked to hyperplasia.

A simple way to reconstruct a human 3-d hypodermis: a useful tool for pharmacological functionality.

BACKGROUND: Adipose tissue engineering has been hampered by the inability to culture mature adipocytes. Adipose-derived stem cell (ASC) culture opens the way for the preparation of human 3-D hypodermis in large quantities. These models play a role in obesity-related active molecules and slimming agent screening. Moreover, they contribute to a better understanding of the mechanisms underpinning obesity. MATERIALS AND METHODS: Freshly extracted ASC from fat tissue were characterized by flow cytometry for CD73, CD90, CD105, HLA-ABC, CD14 and CD45 markers and by Western blot for pref-1. Their differentiation in mature adipocytes was followed by lipid and adiponectin secretion or by oil red O staining and radioimmunoassay. Neosynthesized extracellular matrix (ECM) of 3-D hypodermis was investigated by immunohistochemistry (collagen type I, V and VI) and transmission electron microscopy. RESULTS: Our results demonstrate that the culture of preadipocytes in proliferation medium for 15 days followed by 16 days of culture in differentiation medium allowed production of the thickest single-layer hypodermis in which preadipocytes and mature adipocytes coexist and synthesize adiponectin and ECM components. Functionality of our 3-D single-layer hypodermis was demonstrated both by a 3.5-fold glycerol production after its stimulation with norepinephrine (adrenergic agonist) and by its slimming after caffeine treatment versus the nontreated 3-D hypodermis. CONCLUSION: This economic 3-D model, easy to prepare and giving reproducible results after the treatment of actives, is useful for pharmacotoxicological trials as an alternative to animal experimentation.

Adipose-derived stem cells (ASCs) as a source of endothelial cells in the reconstruction of endothelialized skin equivalents.

Tissue-engineered autologous skin is a potential alternative to autograft for burn coverage, but produces poor clinical responses such as unsatisfactory graft intake due to insufficient vascularization. Endothelialized skin equivalents comprising human umbilical vein endothelial cells (HUVECs) survive significantly longer due to inosculation with the capillaries of the host, but these cells are allogeneic by definition. The aim of this study was to reconstruct an autologous endothelialized skin equivalent by incorporating progenitor or pre-differentiated endothelial cells derived from adipose tissue, easily accessible source for autologous transplantation. Human adipose tissue-derived stem cells were isolated from lipoaspirates and amplified to obtain endothelial progenitor cells, which were subsequently differentiated into endothelial cells. These cells were then seeded along with human fibroblasts into a porous collagen-glycosaminoglycan-chitosan scaffold to obtain an endothelialized dermal equivalent. Then, human keratinocytes give rise to a endothelialized skin equivalent. Immunohistochemistry and transmission electron microscopy results demonstrate the presence of capillary-like tubular structures in skin equivalents comprising pre-differentiated endothelial cells, but not endothelial progenitor cells. The former expressed both EN4 and von Willebrand factor, and Weibel-Palade bodies were detected in their cytoplasm. This study demonstrates that adipose tissue is an excellent source of autologous endothelial cells to reconstruct endothelialized tissue equivalents, and that pre-differentiation of stem cells is necessary to obtain vasculature in such models.

Model of in vitro healing to test the influence of dedifferentiated Crithmum maritimum cells on dermal repair and epidermal regeneration.

BACKGROUND: The aim was to test the influence of dedifferentiated Crithmum maritimum cells (dCMC), totipotent vegetal stem cells, on epidermal regeneration in perfect homeostasis using a skin equivalent (SE) model. MATERIALS AND METHODS: SE are prepared by seeding fibroblasts on a collagen-glycosaminoglycan-chitosan dermal substrate (DS) epidermalized by keratinocytes 3 weeks later. The originality of this present study lies in the systemic administration of dCMC from the moment when fibroblasts are seeded in the DS right through to the reconstruction of the SE. The thickness of the epidermis as well as the number of proliferating cells expressing Ki-67 and layers expressing terminal differentiation marker (filaggrin) were compared in the dCMC-treated SE versus an untreated control group. RESULTS: dCMC accelerated the complete regeneration and differentiation of the epidermis compared to the negative control (35 days instead of 42 days). Histology showed a multilayered, thick and differentiated epithelium after 35 days of culture. The basal and suprabasal layers had increased 4.88 ± 0.41 times versus the negative control (Mann-Whitney U test: p < 0.001). This result was attributed to the greater proliferation of basal cells because the cell numbers expressing the Ki-67 proliferation marker had increased significantly compared to the negative control (Mann-Whitney U test: p < 0.001). Moreover, dCMC allowed the differentiated epithelium to recover because only treated SE expressed the terminal differentiation marker filaggrin. CONCLUSION: Our data show that dCMC enhance epidermal cell grafts by stimulating their regeneration and differentiation in perfect homeostasis. They allow the epidermis to recover its structure for protective functions faster than the negative control.

Zinc-alpha2-glycoprotein: a new biomarker of breast cancer?

BACKGROUND/AIM: Obesity increases the risk of breast cancer. It is established that adipocyte secretions, i.e. adipokines, may play a role in mammary carcinogenesis. We have shown that two major adipokines, leptin and adiponectin, were expressed in mammary adenocarcinoma. PATIENTS AND METHODS: Here, we evaluated zinc-alpha2-glycoprotein (ZAG) expression in tumor (n=55) and healthy (n=6) breast tissue by immunohistochemistry and examined whether it was correlated with that of major adipokines, usual tumor biomarkers (sex steroids receptors, i.e. estrogen (ER) and progesterone; Ki-67; cErb2), or apoptosis markers (Bcl2 and Bax). RESULTS: ZAG expression was detected in ductal carcinoma and normal epithelial adjacent tissue but not in normal tissue of healthy women. In cancer tissue, its expression was correlated positively to leptin receptor and negatively to adiponectin receptor and ER. CONCLUSION: These preliminary results suggest both a relationship between ZAG expression and pathways involving adipokines or estrogen and that ZAG may be a potential breast cancer biomarker.

Optimization of a culture medium for the differentiation of preadipocytes into adipocytes in a monolayer.

UNLABELLED: Our objective was to optimize a medium for preadipocyte differentiation into adipocytes. METHODS: The differentiation medium contains fixed components as well as 7 variable ones. To perform this study, different experiments were designed and the study was carried out in 4 stages. The first two stages tested the influence of serum, dexamethasone, hydrocortisone and an cAMP activator. In the third stage, two new variables were added: rosiglitazone and insulin. In the final stage, the medium selected in stage 3 was validated. The differentiation selection criteria consisted of the number of mature adipocytes and adiponectin secretion. RESULTS: We have shown that each variable was indispensable and that positive interactions occurred between some variables. No negative interactions were found and it was possible to optimize the concentration of each variable. CONCLUSIONS: We selected the following medium, which provides optimal adipocyte size and adiponectin secretion: DMEM/HAMF12+10% Foetal Clone Serum (FCS)+2 nM triiodothyronine+10 nM hydrocortisone +0.5 mM IsoButyl Methyl Xanthine (IBMX)+500 nM dexamethasone+1 microM rosiglitazone+0.15 UI/ml insulin+antibiotics.

[Porous matrix and primary-cell culture: a shared concept for skin and cornea tissue engineering]. / Matrice poreuse et culture de cellules primaires : un même concept pour la reconstruction cutanée et cornéenne.

Skin and cornea both feature an epithelium firmly anchored to its underlying connective compartment: dermis for skin and stroma for cornea. A breakthrough in tissue engineering occurred in 1975 when skin stem cells were successfully amplified in culture by Rheinwald and Green. Since 1981, they are used in the clinical arena as cultured epidermal autografts for the treatment of patients with extensive burns. A similar technique has been later adapted to the amplification of limbal-epithelial cells. The basal layer of the limbal epithelium is located in a transitional zone between the cornea and the conjunctiva and contains the stem cell population of the corneal epithelium called limbal-stem cells (LSC). These cells maintain the proper renewal of the corneal epithelium by generating transit-amplifying cells that migrate from the basal layer of the limbus towards the basal layer of the cornea. Tissue-engineering protocols enable the reconstruction of three-dimensional (3D) complex tissues comprising both an epithelium and its underlying connective tissue. Our in vitro reconstruction model is based on the combined use of cells and of a natural collagen-based biodegradable polymer to produce the connective-tissue compartment. This porous substrate acts as a scaffold for fibroblasts, thereby, producing a living dermal/stromal equivalent, which once epithelialized results into a reconstructed skin/hemicornea. This paper presents the reconstruction of surface epithelia for the treatment of pathological conditions of skin and cornea and the development of 3D tissue-engineered substitutes based on a collagen-GAG-chitosan matrix for the regeneration of skin and cornea.

Does adipose tissue cultured with collagen matrix and preadipocytes give comparable results to the standard technique in plastic surgery?

INTRODUCTION: Repairing contour defects is a challenge in plastic surgery. Different filling materials have been used with inadequate results and complications. The autologous fat transfer is the standard technique at the moment, but adipose tissue reserves are limited. The aim of our study was to compare in vivo on an animal model, preadipocytes cultured in a collagen scaffold versus adipose tissue transferred by the usual surgical technique. MATERIALS AND METHODS: In order to compare adipocytes resulting from the differentiation of preadipocytes with those of purified adipose tissue, we implanted them in 10 nude mice. The preadipocytes were implanted using a collagen scaffold as intermediary and the adipose tissue following the plastic surgery protocol described by SR Coleman. After 8 weeks, tissue fragments were explanted and analysed after staining with HPS, Oil Red O and labelling with human anti-vimentin antibodies. RESULTS: The scaffold seeded with preadipocytes had the macroscopic appearance of adipose tissue with peripheral neovascularisation. The preadipocytes had been transformed into mature adipocytes. Purified adipose tissue also presented peripheral neovascularisation. Numerous mature adipocytes were found. There was an abundant murine extracellular matrix since anti-vimentin labelling was negative. CONCLUSION: This experimental study showed that adipose tissue engineering is feasible and gives comparable results to fat grafting. It allows a better understanding of the sequence of events following the transfer of adipose tissue. It provides not only volume but also undeniable stimulation, leading to significant thickening of the extracellular matrix.

Influence of negative pressure when harvesting adipose tissue on cell yield of the stromal-vascular fraction.

Adipose tissue is the standard autologous filling material used in plastic surgery today. At the same time it is also a source of mesenchymal stem cells, situated in the Stromal-Vascular Fraction (SVF) and easy to obtain in large quantities. The method of harvesting adipose tissue is an important stage for cell survival. So far, comparative studies on harvesting techniques have only concerned MTT cell viability of mature adipocytes. The aim of our study was to determine the influence of pressure on the yield of SVF cells in relation to the syringe aspiration technique which is the standard technique in plastic surgery. For this, six different harvesting conditions were tested on 3 patients. For each condition, a sample was taken from the trochanter region with the help of a 3 mm cannula, manual aspiration by a 10 ml syringe; wall suction; the traditional pump suction at -350 and -700 mmHg; the power assisted liposuction at -350 and -700 mmHg. Cell yield with a pressure of -350 mmHg, assisted or not, was greater than that obtained at -700 mmHg and significantly superior to aspiration with a syringe (p<0.05). At -350 mmHg, the use of power-assisted liposuction gave better results for two out of three patients when compared to non-power-assisted liposuction. Negative pressure is a factor influencing the number of SVF cells harvested.

A congenital hand deformity: Dupuytren's disease.

A 10-month-old child presented with a lack of extension at the distal interphalangeal joint. Despite the absence of trauma, a provisional diagnosis of mallet finger led to treatment using a short dorsal splint. Four months later the flexion had increased and included the proximal interphalangeal joint. Palpation revealed a palmar cord on the lateral aspect of the finger. Surgery disclosed a typical Dupuytren cord and the histology supported this diagnosis. There was no known family history of the disease. There was no sign of recurrence 27 months after surgery in this case of Dupuytren's disease that was present at birth.