Reducing pain and opioid consumption after body contouring of the breast by application of a perioperative nerve block: a systematic review.

BACKGROUND: Pain in the postoperative body contouring patient has traditionally been managed with narcotic medication. In an effort to minimize side effects and prevent addiction, plastic surgeons are searching for novel ways to provide adequate analgesia, one of which is nerve blocks. This study was conducted with a meta-analysis that evaluates the efficacy of these blocks for patients who undergo breast surgery. METHODS: A search of the PubMed/MEDLINE database for articles including the terms "postoperative analgesia" OR "postoperative pain management" AND "in plastic surgery" OR "in cosmetic surgery" OR "in elective surgery" in February 2019 generated five studies on elective breast augmentation and reduction mammoplasty that reported pain scores and quantities of opioids consumed. Independent samples t-tests, one-way analysis of variance, and a random effects model were implemented for evaluation. RESULTS: A total of 317 patients were identified as having undergone body contouring of the breast, about half of which received a nerve block. Pain scores on a 1-10 scale and opioid dose-equivalents were calculated. Those who were blocked had an average score of 2.40 compared to 3.64 for those who did not (P<0.001), and required an average of 5.20 less narcotic doses (P<0.001). Pain relief following subpectoral augmentation was best achieved with type-II blocks as opposed to type-I and type-II with serratus plane (P<0.001). CONCLUSIONS: The opioid epidemic has extended to all surgical specialties. Implementation of a nerve block seems to be an efficacious and cost-effective mechanism to not only help with postoperative pain, but also lower the need for narcotics, especially in subpectoral augmentation.

Trends in flap reconstruction of pelvic oncologic defects: Analysis of the national inpatient sample.

BACKGROUND: Flap reconstruction of radiated pelvic oncologic defects decreases perineal wound-healing complications. How widely and how often reconstructions are performed, and how technical mastery and improved perioperative care has affected outcomes, is unknown. Our objective is to 1) provide a comprehensive evaluation of national trends in flap reconstruction of pelvic oncologic defects and 2) compare complications and length of stay (LOS) in patients with/without reconstruction. METHODS: The National Inpatient Sample (NIS) database was queried (1998-2014) for patients diagnosed with cancer, primarily of the rectum and anus, who underwent abdominoperineal resection (APR) or pelvic exenteration (PE). Differences in complications and LOS were compared between patients with flap reconstruction versus primary closure. Regional and hospital outcomes were also analyzed. RESULTS: The cohort included 117,923 adult patients; 3,673 (3.1%) underwent flap reconstruction. Flap reconstruction rates increased from 0.8% in 1998 to 9.8% in 2014. Extirpative procedures decreased 37.4% from 1998 to 2014. Flap reconstruction decreased risk of wound breakdown (OR 0.87; p = 0.0029) and need for secondary closure of dehiscence (OR 0.82; p = 0.0023) between periods 1998-2009 and 2010-2014. Median LOS was higher for flap patients (median [IQR] of 9.8 [7.2,14.8] vs. 7.9 [6.1-11.0; p < 0.0001) and decreased over time. CONCLUSIONS: The use of flap reconstruction for pelvic oncologic defects increased from 1998 to 2014, with a reduction in LOS. Following flap reconstruction, overall complications are higher, but wound breakdown and dehiscence requiring reclosure are decreasing, suggesting technique maturation. We anticipate flap reconstruction rates will increase with further improvement in patient outcomes.

Comparison of wound strength, histologic, and aesthetic outcomes after microsurgical versus conventional skin closure in a rat model.

The purpose of this study was to compare the healing, strength, and cosmetic outcome of linear incisions after repair with the naked eye, surgical loupes, or a surgical microscope. Two parallel incisions were made on the dorsal skin of Sprague-Dawley rats (n = 36) and the rats randomized into four groups. A single surgeon repaired the incisions using 5-0 poliglecaprone in a running subcuticular pattern using the naked eye (Group I), surgical loupes with 2.5× magnification (Group II), surgical microscope with 5-10× magnification (Group III), and 6-0 poliglecaprone with a surgical microscope (Group IV). Rats were sacrificed at 1, 3, and 6 weeks. At each time point, the tensile strength of each closure was assessed. Macroscopic outcomes were evaluated using the Vancouver Scar Scale (VSS) and histology assessed by a blinded observer. Microscope closure took significantly longer than closure with the naked eye (p < 0.05). There was no significant difference in tensile strength or VSS ratings between the closure methods at any of the time points. On histopathologic analysis, there were a greater number of inflammatory cells and fibroblasts in the 6-0 microscope closure group versus the naked eye closure group at week 3 (p ≤ 0.05). In conclusion, wound repair under magnification did not yield a significant difference in cosmesis or wound tensile strength, but did increase operative time. Moreover, there was a trend toward increased inflammation with microscope-assisted closures, perhaps due to the increased suture burden.

Review of the Pathways Involved in the Osteogenic Differentiation of Adipose-Derived Stem Cells.

Grafts and prosthetic materials used for the repair of bone defects are often accompanied by comorbidity and rejection. Therefore, there is an immense need for novel approaches to combating the issues surrounding such defects. Because of their accessibility, substantial proportion, and osteogenic differentiation potential, adipose-derived stem cells (ASCs) make for an ideal source of bone tissue in regenerative medicine. However, efficient induction of ASCs toward an osteoblastic lineage in vivo is met with challenges, and many signaling pathways must come together to secure osteoblastogenesis. Among them are bone morphogenic protein, wingless-related integration site protein, Notch, Hedgehog, fibroblast growth factor, vascular endothelial growth factor, and extracellular regulated-signal kinase. The goal of this literature review is to conglomerate the present research on these pathways to formulate a better understanding of how ASCs are most effectively transformed into bone in the context of tissue engineering.

Defining hydrogel properties to instruct lineage- and cell-specific mesenchymal differentiation.

The maintenance and direction of stem cell lineage after implantation remains challenging for clinical translation. Aggregation and encapsulation into instructive biomaterials after preconditioning can bolster retention of differentiated phenotypes. Since these procedures do not depend on cell type or lineage, we hypothesized we could use a common, tunable platform to engineer formulations that retain and enhance multiple lineages from different cell populations. To test this, we varied alginate stiffness and adhesive ligand content, then encapsulated spheroids of varying cellularity. We used Design-of-Experiments to determine the effect of these parameters and their interactions on phenotype retention. The combination of parameters leading to maximal differentiation varied with lineage and cell type, inducing a 2-4-fold increase over non-optimized levels. Phenotype was also retained for 4 weeks in a murine subcutaneous model. This widely applicable approach can facilitate translation of cell-based therapies by instructing phenotype in situ without prolonged induction or costly growth factors.

Differences in Complication Rates of Gluteoplasty Procedures That Utilize Autologous Fat Grafting, Implants, or Local Flaps.

BACKGROUND: Gluteoplasty (gluteal augmentation) procedures are increasing in popularity, but there is not a universally accepted technique to produce optimal outcomes while minimizing risk. In this systematic review, we perform a meta-analysis to evaluate rates of complication from autologous fat grafting, implants, and local flaps, which are the three most common gluteoplasty operations. METHODS: A search of the PubMed/MEDLINE database for articles including the terms "gluteoplasty" OR "gluteal augmentation" OR "buttock augmentation" OR "Brazilian butt lift" OR "gluteal autologous fat graft" OR "buttock autologous fat graft" OR "gluteal implant" OR "buttock implant" OR "gluteal flap" OR "buttock flap" generated 229 articles. This number was brought down to 134 after initial screening by title. Inclusion criteria then removed those not written in English, those without access to the full text, those without extractable data on complications, and duplicates, leaving 46 articles to examine. RESULTS: A total of 4362 patients who underwent gluteoplasty between 1992 and 2017 were found. The overall complication rate was 12.4%. Implants had the highest rate (31.4%), whereas fat grafting had the lowest (6.8%); flaps were intermediate (23.1%). A χ test yielded a statistically significant (P < 0.001) nonindependent relationship between combined complication rate and type of surgery. Individual complications, such as asymmetry, capsular contracture, fat embolism, hematoma, infection, necrosis, pain, seroma, wide scar formation, and wound dehiscence, were also analyzed. CONCLUSIONS: Fat grafting by plastic surgeons might be the best option for gluteoplasty with regard to complications. In certain cases, however, there may only exist one choice for an operation because of anatomical limitations, which predisposes patients to those associated complications.

Cell-secreted extracellular matrix, independent of cell source, promotes the osteogenic differentiation of human stromal vascular fraction.

Lipoaspirates contain a readily accessible heterogeneous cell source for use in bone regeneration collectively referred to as the stromal vascular fraction (SVF). However, the osteogenic potential of SVF is inferior to other progenitor cell populations, thereby requiring alternative strategies to potentiate its effective use in cell-based therapies of bone repair. Cell-secreted extracellular matrix (ECM) is a promising substrate to guide cell phenotype or for use in biomaterial design, yet the instructional capacity of ECMs produced by various cell types is unknown. To determine whether the bioactivity of cell-secreted ECM was dependent on cell source, we assessed the osteogenic response of human SVF on ECMs secreted by bone marrow-derived mesenchymal stem cells (MSCs), adipose stromal cells (ASCs), and human dermal fibroblasts (HDFs). Tissue culture plastic (TCP), type I collagen, and ECM induced expression of integrin subunits α2, α5, and ß1 in SVF, yet seeding efficiency was only improved on MSC-derived ECM. Regardless of ECM source, SVF deposited over 8- and 1.3-fold more calcium compared to TCP and collagen-coated controls, respectively. Flow cytometry confirmed that SVF cultured on ECM retained CD31 and CD34 positive cell populations better than TCP. After depleting accessory cells, ASCs deposited significantly less calcium compared to donor-matched SVF. This function was partially restored in the presence of MSC-derived ECM when donor-matched endothelial cells (ECs) were added in an ASC/EC co-culture, confirming a role for ECs in osteogenic differentiation. These findings support the use of cell-derived ECM as a means to promote cell retention and osteogenic differentiation of SVF.

Fat Graft Safety after Oncologic Surgery: Addressing the Contradiction between In Vitro and Clinical Studies.

BACKGROUND: The authors investigate the in vitro and in vivo interaction of human breast cancer cells and human adipose-derived stem cells to address the controversy on the safety of postmastectomy fat grafting. METHODS: The authors co-cultured human adipose-derived stem cells and MDA-MB-231 breast cancer cells in an in vitro cell migration assay to examine the migration of breast cancer cells. In the in vivo arm, the authors injected breast cancer cells (group I), human breast cancer cells plus human adipose-derived stem cells (group II), human breast cancer cells plus human fat graft (group III), and human breast cancer cells plus human fat graft plus human adipose-derived stem cells (group IV) to the mammary fat pads of female nude mice (n = 20). The authors examined the tumors, livers, and lungs histologically after 2 weeks. RESULTS: Migration of breast cancer cells increased significantly when co-cultured with adipose-derived stem cells (p < 0.05). The tumor growth rate in group IV was significantly higher than in groups I and II (p < 0.05). The tumor growth rate in group III was also higher than in groups I and II, but this difference was not statistically significant (p > 0.05). Histologically, there was no liver/lung metastasis at the end of 2 weeks. The vascular density in the tumors from group IV was significantly higher than in other groups (p < 0.01). CONCLUSION: The injection of breast cancer cells, fat graft, and adipose-derived stem cells together increases breast cancer xenograft growth rates significantly.

The Effects of Adipose-Derived Stem Cells Differentiated Into Endothelial Cells and Osteoblasts on Healing of Critical Size Calvarial Defects.

Delayed vascularization and resultant resorption limits the clinical use of tissue engineered bony constructs. The objective of this study is to develop a strategy to accelerate the neovascularization of tissue-engineered bony constructs using endothelial differentiated adipose-derived stem cells (ASC). The authors harvested ASC from inguinal fat pads of male Lewis rats (n = 5) and induced toward endothelial and osteoblastic lineages. The authors created critical size calvarial defects on male Lewis rats (n = 30) and randomized the animals into 4 groups. For the repair of the defects the authors used hydroxyapatite/poly(lactide-co-glycolide) [HA-PLG] scaffolds in group I, HA-PLG scaffolds seeded with ASC in group II, HA-PLG scaffolds seeded with ASC-derived endothelial cells in group III, and HA-PLG scaffolds seeded with ASC-derived osteoblasts in group IV. The authors evaluated the bone healing histologically and with micro-computed tomography (CT) scans 8 weeks later. Adipose-derived stem cells exhibited the characteristics of endothelial and osteogenic lineages, and attached on HA-PLG scaffolds after differentiation. Micro-CT analysis revealed that highest bone mineral density was in group IV (1.46 ± 0.01 g/cm) followed by groups III (1.43 ± 0.05 g/cm), I (1.42 ± 0.05 g/cm), and II (1.3 ± 0.1 g/cm). Hematoxylin-Eosin and Masson Trichrome staining revealed similar results with the highest bone regeneration in group IV followed by groups II, III, and I. Regenerated bone in group IV also had the highest vascular density, but none of these differences achieved statistical significance (P > 0.05). The ASC-derived endothelial cells and osteoblasts provide a limited increase in calvarial bone healing when combined with HA-PLG scaffolds.

Comparison of two cadaveric acellular dermal matrices for immediate breast reconstruction: A prospective randomized trial.

AlloDerm RTU® and AlloMaxTM are two acellular dermal matrices (ADMs) used in implant-based breast reconstruction. In this study, we examined whether different processing methods for the ADMs lead to a disparity in histologic, clinical, and financial outcomes after breast reconstruction. Thirty patients undergoing implant-based breast reconstruction were randomized into AlloMax or AlloDerm arms (n = 15, each). ADM was placed at the time of immediate reconstruction. Patients were evaluated for complications on postoperative days 7, 14, and 30. During implant exchange, ADM biopsies were taken and compared histologically for vascular and cellular infiltration. Patient satisfaction was evaluated using the BRECON-31 questionnaire 1 year after implant exchange. A cost analysis was performed comparing the two ADMs. Patient demographics and complication rates were similar between the two groups (p > 0.05). Histologically, vessel density and fibroblast/inflammatory cell infiltrate were greater on the dermal side than on the implant side (p < 0.01) in both ADMs, suggesting greater vascular and cellular in-growth from the dermal side. Vessel density in the middle portion of the Allomax biopsies was significantly higher than the same site in the Alloderm biopsies (p < 0.05). The extent of fibroblast/inflammatory cell infiltration was similar in both arms (p > 0.05). The BRECON-31 satisfaction questionnaire yielded similar responses across all metrics between the two study arms. The negotiated price was slightly different when comparing the two ADMs, with no significant difference in ADM reimbursement. In this study, AlloDerm RTU and AlloMax were successfully used for implant-based breast reconstruction with comparable outcomes.

Comparison of Endothelial Differentiation Capacities of Human and Rat Adipose-Derived Stem Cells.

BACKGROUND: The authors compared the endothelial differentiation capacities of human and rat adipose-derived stem cells to determine whether human adipose-derived stem cells can be a source of endothelial cells clinically. METHODS: Human and rat adipose-derived stem cells were harvested and characterized with flow cytometry and trilineage differentiation. Cells from passages III through V were fed with endothelial cell differentiation medium for up to 3 weeks. Cells were harvested after 1, 2, and 3 weeks, and endothelial differentiation was evaluated with quantitative reverse-transcriptase polymerase chain reaction, flow cytometry, and angiogenic sprouting assays. RESULTS: Both human and rat adipose-derived stem cells were CD90, CD44, and CD31 before differentiation. The cells were successfully differentiated into adipogenic, osteogenic, and chondrogenic lineages. Expression of endothelial cell-specific genes peaked at the second week of differentiation in both human and rat cells. The fold changes in expression of CD31, vascular endothelial growth factor receptor-1, nitric oxide synthase, and von Willebrand factor genes at week 2 were 0.4 ± 0.1, 34.7 ± 0.3, 2.03 ± 0.25, and 12.5 ± 0.3 respectively, in human adipose-derived stem cells; and 1.5 ± 1.01, 21.6 ± 1.7, 17.9 ± 0.6, and 11.2 ± 1.3, respectively, in rat cells. The percentages of CD31 cells were 0.2, 0.64, and 1.6 in human cell populations and 0.5, 5.91, and 11.5 in rat cell populations at weeks 1, 2, and 3, respectively. Rat adipose-derived stem cell-derived endothelial cells displayed enhanced sprouting capability compared with the human cells. CONCLUSIONS: Human adipose-derived stem cells responded less strongly to EGM-2MV endothelial differentiation medium than did the rat cells. Still, the human cells have the potential to become a clinical source of endothelial cells with modifications in the differentiation conditions.

Developing a Nanoparticle-Delivered High-Efficacy Treatment for Infantile Hemangiomas Using a Mouse Hemangioendothelioma Model.

BACKGROUND: Current treatments for infantile hemangiomas have unpredictable outcomes. The authors' aim was to develop a nanoporphyrin-delivered, high-efficacy treatment for infantile hemangiomas using a mouse hemangioendothelioma model. METHODS: The authors injected mouse hemangioendothelioma cells intradermally to axillary regions of 5-week-old, female, nude mice (n = 19) to induce hemangioendothelioma growth. They documented nanoporphyrin accumulation in hemangioendotheliomas using positron emission tomography. For the treatment study, the authors randomized hemangioendothelioma-bearing nude mice (n = 9) into three groups (n = 3 each). Group I received only saline injections. Group II received only laser treatment after saline injection, and group III received laser treatment after nanoporphyrin injection through the tail vein. The authors followed up the treatment response with digital caliper measurements. RESULTS: Hemangioendotheliomas started to grow approximately 1 week after inoculation and resembled infantile hemangiomas histologically. Nanoporphyrin uptake in hemangioendotheliomas was 19.7 ± 2.2, 16.7 ± 2.02, 8.4 ± 0.3, and 4.9 ± 0.6 percent injected dose per gram of tissue at 3, 6, 24, and 48 hours after injection, respectively. Nanoporphyrin uptake was significantly higher than in blood at 24 and 48 hours after injection (p < 0.05). Results of ex vivo biodistribution study were consistent with positron emission tomographic imaging. Hemangioendotheliomas in group III started to regress 1 day after the treatment and disappeared totally by day 21. The difference between tumor volumes in group III and other groups was significant on days 17 and 21 (p < 0.05). CONCLUSIONS: Nanoporphyrin accumulated in hemangioendotheliomas at high concentrations, enabling a high-efficacy photodynamic therapy. Given the similarities between hemangioendotheliomas and infantile hemangiomas, this treatment potentially can be a high-efficacy treatment for infantile hemangiomas.

In Vitro Effects of Adipose-Derived Stem Cells on Breast Cancer Cells Harvested From the Same Patient.

INTRODUCTION: Fat grafting for breast cancer (BrCa) reconstruction and breast augmentation has become increasingly more popular. A major area of debate and controversy is the effect of adipose-derived stem cells (ASCs) on remnant or undetected BrCa cells. We investigate the in vitro response of BrCa to ASCs in a coculture model with regards to cell migration. METHODS: The study was approved by the institutional review board. BrCa and adipose tissue specimens either from subcutaneous breast tissue or abdominal lipoaspirate were obtained from the same patient. BrCa cells and ASCs were harvested with either explant culture and/or enzymatic digestion. Tissues were grown in cell culture flasks until adequate cell libraries were established. Adipose-derived stem cells from adipose specimens were characterized with flow cytometry. Immunofluorescence (IF) staining of the initial cell population harvested from the BrCa specimens confirmed the presence of CD24, an epithelial marker of BrCa. A homogenous CD 24+/CD 90- BrCa cell population was obtained with flowcytometric cell sorting. The in vitro migration of BrCa cells was examined in coculture with and without ASCs. RESULTS: Adipose-derived stem cells harvested from the adipose specimens were positive for mesenchymal stem cell markers CD 105, CD 90, CD 73, and CD 44 and negative for lymphocyte cell marker CD 34 and leukocyte marker CD 45. The percentage of the CD 24+/CD 90- BrCa cells in the initial cell population harvested from BrCa specimens was 0.61%. The BrCa cells morphologically had large nuclei and small cytoplasm in clusters under the light microscope, suggesting a cancer cell phenotype. CD 24 expression on the surface of BrCa cells was confirmed with IF staining. The number of BrCa cells migrated in ASCs coculture was approximately 10 times higher than the number of BrCa cells migrated in BrCa cell only cultures. CONCLUSIONS: Adipose-derived stem cells significantly increase the migration capacity of BrCa cells in vitro in cocultures. This should be taken into consideration when performing fat grafting to the breast especially in patients with a history of BrCa or strong family history of BrCa.

Assessing safety of negative-pressure wound therapy over pedicled muscle flaps: A retrospective review of gastrocnemius muscle flap.

The use of negative-pressure wound therapy (NPWT) for management of open wounds and immobilization of split-thickness skin grafts (STSGs) over wounds has been well described. However, there is a concern for potential compromise of flap viability when NPWT is used for skin grafts over pedicled muscle flaps. We have used NPWT to immobilize STSGs in eight patients who underwent a pedicled gastrocnemius muscle flap operation in our department. We applied a negative pressure of -75 mmHg on the muscle flaps for 5 days postoperatively. All wounds healed successfully, with a 97.5 ± 5.5% mean STSG uptake. No flap necrosis was observed. In our series, the use of NPWT for fixation of STSGs over pedicled gastrocnemius muscle flap was effective and had no negative impact on flap viability.

The Oncologic Safety of Breast Fat Grafting and Contradictions Between Basic Science and Clinical Studies: A Systematic Review of the Recent Literature.

Fat grafting is increasingly popular and is becoming a common practice in plastic surgery for postmastectomy breast reconstruction and aesthetic breast augmentation; however, concerns over the oncologic safety remains a controversial and hot topic among scientists and surgeons. Basic science and laboratory research repeatedly show a potentially dangerous effect of adipose-derived stem cells on breast cancer cells; however, clinical research, although limited, continually fails to show an increase in breast cancer recurrence after breast fat grafting, with the exception of 1 small study on a subset patient population with intraepithelial neoplasm of the breast. The aim of this review is to summarize the recent conflicting basic science and clinical data to better understand the safety of breast fat grafting from an oncological perspective.

Deep Inferior Epigastric Artery Perforator Flap Breast Reconstruction without Microsurgery Fellowship Training.

BACKGROUND: Deep inferior epigastric artery perforator (DIEP) flap breast reconstruction requires complex microsurgical skills. Herein, we examine whether DIEP flap breast reconstruction can be performed safely without microsurgical fellowship training. METHODS: A total of 28 patients and 34 DIEP flaps were included in the study. We reviewed the medical records of patients for donor site and flap-related complications and analyzed the correlation between the complications and preoperative risk factors. We also performed a literature review to compare complication rates in our series with the literature. RESULTS: We observed total flap necrosis in 1 patient (2.9%), partial flap necrosis in 5 patients (14.7%), infection in 1 patient (2.9%), hematoma/seroma in 3 patients (8.8%), donor site complications in 5 patients (18.5%), venous occlusion in 4 patients (11.7%), and arterial occlusion in 1 patient (2.9%). We did not observe any correlation between complications and preoperative risk factors. Literature review yielded 18 papers that met our inclusion criteria. Partial flap necrosis rate was significantly higher in our series compared with literature (14.7% vs 1.6%, P = 0.003). Venous complication rate was marginally higher in our series compared with literature (11.7% vs 3.3%, P = 0.057). However, total flap loss rate in our series was comparable with the literature (2.9% vs 2.2%, P = 0.759). CONCLUSION: With proper training during plastic surgery residency, DIEP flap can be performed with acceptable morbidity.

Irradiated superficial femoral artery rupture after free flap: a case report and review of the literature.

Radical oncologic resection can result in large soft tissue defects with exposure of underlying vessels. Unless immediately covered with viable soft tissue, these vessels are vulnerable to desiccation from air exposure and mechanical trauma. Local radiation treatment also contributes to a decline in vessel wall strength. We present an index case of a patient with prolonged exposure of her femoral bone and superficial femoral artery after an initial failed reconstruction of a soft tissue sarcoma resection defect. We provided coverage using a free latissimus dorsi muscle flap. Two weeks after the initial free flap operation, the patient was readmitted to emergency service with profuse bleeding from beneath the free flap. Intraoperative inspection revealed a 2-cm defect of the irradiated superficial femoral artery. The defect was repaired with cryopreserved human arterial graft, and the flap was reset. This case highlights the importance of immediate coverage of soft tissue defects after oncologic resection. If any vessels are left exposed, they should be closely inspected before a delayed flap coverage to rule out future sources of bleeding that may jeopardize the outcomes of an otherwise successful free flap operation.

The key components of Schwann cell-like differentiation medium and their effects on gene expression pattern of adipose-derived stem cells.

BACKGROUND: Schwann cell-like cells differentiated from adipose-derived stem cells may have an important role in peripheral nerve regeneration. Herein, we document the individual effects of growth factors in Schwann cell-like differentiation medium. METHODS: There were 6 groups in the study. In the control group, we supplemented the rat adipose-derived stem cells with normal cell culture medium. In group 1, we fed the cells with Schwann cell-like differentiation medium (normal cell culture medium supplemented with platelet-derived growth factor, basic fibroblast growth factor, forskolin, and glial growth factor). In the other groups, we removed the components of the medium one at a time from the differentiation medium so that group 2 lacked glial growth factor, group 3 lacked forskolin, group 4 lacked basic fibroblast growth factor, and group 5 lacked platelet-derived growth factor. We examined the expression of the Schwann cell-specific genes with quantitative reverse transcription polymerase chain reaction and immunofluorescence staining in each group. RESULTS: Groups 3 and 4, lacking forskolin and basic fibroblast growth factor, respectively, had the highest expression levels of integrin-ß4, and p75. Group 1 showed a 3.2-fold increase in the expression of S100, but the expressions of integrin-ß4 and p75 were significantly lower compared to groups 3 and 4. Group 2 [glial growth factor (-)] did not express significant levels of Schwann cell-specific genes. The gene expression profile in group 4 most closely resembled Schwann cells. Immunofluorescence staining results were parallel with the quantitative real-time polymerase chain reaction results. CONCLUSIONS: Glial growth factor is a key component of Schwann cell-like differentiation medium.