Omics Studies of Tumor Cells under Microgravity Conditions.

Cancer is defined as a group of diseases characterized by abnormal cell growth, expansion, and progression with metastasis. Various signaling pathways are involved in its development. Malignant tumors exhibit a high morbidity and mortality. Cancer research increased our knowledge about some of the underlying mechanisms, but to this day, our understanding of this disease is unclear. High throughput omics technology and bioinformatics were successful in detecting some of the unknown cancer mechanisms. However, novel groundbreaking research and ideas are necessary. A stay in orbit causes biochemical and molecular biological changes in human cancer cells which are first, and above all, due to microgravity (µg). The µg-environment provides conditions that are not reachable on Earth, which allow researchers to focus on signaling pathways controlling cell growth and metastasis. Cancer research in space already demonstrated how cancer cell-exposure to µg influenced several biological processes being involved in cancer. This novel approach has the potential to fight cancer and to develop future cancer strategies. Space research has been shown to impact biological processes in cancer cells like proliferation, apoptosis, cell survival, adhesion, migration, the cytoskeleton, the extracellular matrix, focal adhesion, and growth factors, among others. This concise review focuses on publications related to genetic, transcriptional, epigenetic, proteomic, and metabolomic studies on tumor cells exposed to real space conditions or to simulated µg using simulation devices. We discuss all omics studies investigating different tumor cell types from the brain and hematological system, sarcomas, as well as thyroid, prostate, breast, gynecologic, gastrointestinal, and lung cancers, in order to gain new and innovative ideas for understanding the basic biology of cancer.

Interdisciplinary aspects of abdominal and plastic surgery - what does the (abdominal) surgeon need to know?

Introduction: The aim was to reflect the established interdisciplinary aspects of general/abdominal and plastic surgery by means of a narrative review. Methods: (i) With specific references out of the medical literature and (ii) own clinical and perioperative as well as operating technical and tactical management experiences obtained in surgical daily practice, we present a choice of options for interdisciplinary cooperation that could be food of thought for other surgeons. Content: - Decubital ulcers require pressure relieve, debridement and plastic surgery coverage, e.g., by a rotation flap plasty, V-Y flap or "tensor-fascia-lata" (TFL) flap depending on localization (sacral/gluteal defects, ischiadic tuber). - Coverage of soft tissue defects, e.g., after lymph node dissection, tumor lesions or disturbance of wound healing can be managed with fasciocutaneous or muscle flaps. - Bariatric surgery: Surgical interventions such as butt lift, tummy tuck should be explained and demonstrated in advance and performed commonly after reduction of the body weight. - Abdominoperineal rectum extirpation (APE): Holm's procedure with greater circumferential extent of resection at the mesorectum and the insertion site of the levator muscle at the anal sphicter muscle resulting in a substantial defect is covered by myocutaneous flap plasty. - Hernia surgery: Complicated/recurrent hernias or abdominal wall defect can be covered by flap plasty to achieve functional reconstruction, e.g., using innervated muscle. Thus, abdominal wall can respond better onto changes of pressure and tension. - Necrotising fasciitis: Even in case of suspicious fasciitis, an immediate radical debridement must be performed, followed by intensive care with calculated antibiotic treatment; after appropriate stabilization tissue defects can be covered by mesh graft of flap plasty. - Soft tissue tumor lesions cannot be resected with primary closure to achieve appropriate as intended R0 resection status by means of local radical resection all the time - plastic surgery expertise has to be included into interdisciplinary tumor concepts. - Liposuction/-filling: Liposuction can be used with aesthetic intention after bariatric surgery or for lipedema. Lipofilling is possible for reconstruction and for aesthetic purpose. - Reconstruction of lymphatic vessels: Lymphedema after tumor operations interrupting or blocking lymphatic drainage can be treated with microsurgical reconstructions (such as lympho-venous anastomoses, lympho-lymphatic anastomoses or free microvascular lymph node transfer). - Microsurgery: It is substantial part of modern reconstructive plastic surgery, i.e., surgery of peripheral nerves belongs to this field. For visceral surgery, it can become important for reconstruction of the recurrent laryngeal nerve. - Sternum osteomyelitis: Radical debridement (eventually, complete sternal resection) with conditioning of the wound by vacuum-assisted closure followed by plastic surgery coverage can prevent chronification, threatening mediastinitis, persisting infectious risk, long-term suffering or limited quality of life. Summary: The presented selection of single topics can only be an excerpt of all the options for surgical cooperation in daily clinical and surgical practice. Outlook: An interdisciplinary approach of abdominal and plastic surgery is characterized by a highly developed cooperation in common surgical interventions including various techniques and tactics highlighting the specifics of the two fields.

Angiosarcoma on Top of a Meningioma Mimicking a Transosseous Meningioma: an Interdisciplinary Point of View.

Cutaneous angiosarcoma is a rare type of sarcoma with poor prognosis. Meningioma is the most frequent benign intracranial tumor. Despite the fact that meningiomas are mostly benign, bone and skin can be infiltrated. We report the rare case of an angiosarcoma on top of a meningioma with hyperostosis at exactly the same location mimicking a transosseous growth of a meningioma. An 84-year-old man presented with progressive swelling and ulcerous lesion of the forehead. The patient underwent surgery in an interdisciplinary setting together with a plastic surgeon, including resection of the intracranial tumor and infiltrated bone and skin. To the best of our knowledge, this is the only reported case of a meningioma and angiosarcoma in direct neighborhood. A preoperative biopsy of the skin tumor would have led initially to the correct diagnosis of an angiosarcoma and would have allowed a better planning of the operation and extent of resection.

The Fight against Cancer by Microgravity: The Multicellular Spheroid as a Metastasis Model.

Cancer is a disease exhibiting uncontrollable cell growth and spreading to other parts of the organism. It is a heavy, worldwide burden for mankind with high morbidity and mortality. Therefore, groundbreaking research and innovations are necessary. Research in space under microgravity (µg) conditions is a novel approach with the potential to fight cancer and develop future cancer therapies. Space travel is accompanied by adverse effects on our health, and there is a need to counteract these health problems. On the cellular level, studies have shown that real (r-) and simulated (s-) µg impact survival, apoptosis, proliferation, migration, and adhesion as well as the cytoskeleton, the extracellular matrix, focal adhesion, and growth factors in cancer cells. Moreover, the µg-environment induces in vitro 3D tumor models (multicellular spheroids and organoids) with a high potential for preclinical drug targeting, cancer drug development, and studying the processes of cancer progression and metastasis on a molecular level. This review focuses on the effects of r- and s-µg on different types of cells deriving from thyroid, breast, lung, skin, and prostate cancer, as well as tumors of the gastrointestinal tract. In addition, we summarize the current knowledge of the impact of µg on cancerous stem cells. The information demonstrates that µg has become an important new technology for increasing current knowledge of cancer biology.

Combined iliac crest graft and short-scar pectoralis major flap for clavicular non-union reconstruction.

Recently, we reported defect coverage in the clavicular region with a scar-sparing pectoralis major flap. We successfully combine this flap with a clavicular reconstruction by an iliac bone graft for non-union now. We propose this reconstructive combination for cases of clavicular non-union with lack of soft tissue coverage.

Cancer Studies under Space Conditions: Finding Answers Abroad.

In this review article, we discuss the current state of knowledge in cancer research under real and simulated microgravity conditions and point out further research directions in this field. Outer space is an extremely hostile environment for human life, with radiation, microgravity, and vacuum posing significant hazards. Although the risk for cancer in astronauts is not clear, microgravity plays a thought-provoking role in the carcinogenesis of normal and cancer cells, causing such effects as multicellular spheroid formation, cytoskeleton rearrangement, alteration of gene expression and protein synthesis, and apoptosis. Furthermore, deleterious effects of radiation on cells seem to be accentuated under microgravity. Ground-based facilities have been used to study microgravity effects in addition to laborious experiments during parabolic flights or on space stations. Some potential 'gravisensors' have already been detected, and further identification of these mechanisms of mechanosensitivity could open up ways for therapeutic influence on cancer growth and apoptosis. These novel findings may help to find new effective cancer treatments and to provide health protection for humans on future long-term spaceflights and exploration of outer space.

A case of upper lip necrosis after cosmetic injection of hyaluronic acid soft-tissue filler-Does capillary infarction play a role in the development of vascular compromise, and what are the implications?

Facial rejuvenation with injectable filler substances is a frequently applied outpatient procedure. However, light, moderate, and even severe complications may occur. A case of tissue necrosis at the upper lip after injection of highly cross-linked hyaluronic acid together with the following salvage procedure is presented here. We discuss this complication with respect to relevant anatomy and physicochemical properties of the filler substance and review the recommendations given in literature for decreasing the likelihood of such an adverse event.

Alteration of Cytoskeleton Morphology and Gene Expression in Human Breast Cancer Cells under Simulated Microgravity.

OBJECTIVE: Weightlessness simulation due to the simulated microgravity has been shown to considerably affect behavior of tumor cells. It is aim of this study to evaluate characteristics of human breast cancer cells in this scaffoldfree 3D culture model. MATERIALS AND METHODS: In this experimental study, the cells were exposed to simulated microgravity in a randompositioning machine (RPM) for five days. Morphology was observed under phase-contrast and confocal microscopy. Cytofilament staining was performed and changes in expression level of cytofilament genes, proliferation/differentiation genes, oncogenes and tumor suppressor genes were detected by quantitative reverse transcription polymerase chain reaction (qRT-PCR), followed by western blot confirmation. RESULTS: After five days, distinct spheroid formation was observed. Rearrangement of the cytoskeleton into spherical shape was visible. VIM gene expression was significantly up-regulated for adherent cells and spheroids (3.3x and 3.6x respectively, P<0.05 each). RHOA also showed significant gene up-regulation for adherent cells and spheroids (3.2x and 3.9x respectively, P<0.05 each). BRCA showed significant gene up-regulation in adherent cells and spheroids (2.1x and 4.1x respectively, P<0.05 each). ERBB2 showed significant gene up-regulation (2.4x, P<0.05) in the spheroids, but not in the adherent cells. RAB27A showed no significant alteration in gene expression. MAPK) showed significant gene up-regulation in adherent cells and spheroids (3.2x, 3.0x, P<0.05 each). VEGF gene expression was down-regulated under simulated microgravity, without significance. Alterations of gene expressions could be confirmed on protein level for vimentin and MAPK1. Protein production was not increased for BRCA1, human epidermal growth factor receptor 2 (HER2) and VEGF. Contradictory changes were determined for RHOA and its related protein. CONCLUSION: Microgravity provides an easy-to handle, scaffold-free 3D-culture model for human breast cancer cells. There were considerable changes in morphology, cytoskeleton shape and gene expressions. Identification of the underlying mechanisms could provide new therapeutic options.

The Role of C-X-C Chemokine Receptor Type 4 (CXCR4) in Cell Adherence and Spheroid Formation of Human Ewing's Sarcoma Cells under Simulated Microgravity.

We studied the behavior of Ewing's Sarcoma cells of the line A673 under simulated microgravity (s-µg). These cells express two prominent markers-the oncogene EWS/FLI1 and the chemokine receptor CXCR4, which is used as a target of treatment in several types of cancer. The cells were exposed to s-µg in a random-positioning machine (RPM) for 24 h in the absence and presence of the CXCR4 inhibitor AMD3100. Then, their morphology and cytoskeleton were examined. The expression of selected mutually interacting genes was measured by qRT-PCR and protein accumulation was determined by western blotting. After 24 h incubation on the RPM, a splitting of the A673 cell population in adherent and spheroid cells was observed. Compared to 1 g control cells, EWS/FLI1 was significantly upregulated in the adherent cells and in the spheroids, while CXCR4 and CD44 expression were significantly enhanced in spheroids only. Transcription of CAV-1 was upregulated and DKK2 and VEGF-A were down-regulated in both, adherent in spheroid cells, respectively. Regarding, protein accumulation EWS/FLI1 was enhanced in adherent cells only, but CD44 decreased in spheroids and adherent cells. Inhibition of CXCR4 did not change spheroid count, or structure. Under s-µg, the tumor marker EWS/FLI1 is intensified, while targeting CXCR4, which influences adhesion proteins, did not affect spheroid formation.

What does a (general and abdominal) surgeon need to know on plastic surgery?

BACKGROUND: Plastic surgery was first introduced as a sub-specialty of general surgery in Germany in 1978. Since then, this surgical subspecialty/discipline has evolved enormous potential, e.g. in collaboration with other disciplines such as general andabdominal surgery. AIM: To highlight and summarize the basic potential, technical options and novel aspects of plastic surgery, which are relevant for the common interdisciplinary surgical strategies of plastic and general as well as abdominal surgery in clinical practice. METHOD: Short and compact narrative review based on 1) a selection of relevant references from the medical scientific literature and 2) surgical experiences obtained in daily practice. R esults (selected corner points): 1) Biological protection procedures in vascular surgery by flap coverage after meticulous debridement with or without autogenic vascular reconstruction are used to overcome infection of a vascular prosthesis, a serious problem, associated with the risk of anastomotic rupture and bleeding by transfer of immunological competence due to tissue coverage and finally to induce healing in the area of an infected vascular prosthesis. 2) Fistula treatment for aorto-tracheal or aorto-duodenal fistulas, a big challenge for the referring general surgeon, can be treated by flap coverage, i.e. interposition of the pectoralis-major flap and the omentum-majus flap, respectively. 3) With regard to nerve surgery, encouraging results have been reported after early microsurgical recurrent laryngeal nerve repair, i.e. improved subjective voice quality or reconstitution of respiratory capacity in diaphragmatic. 4) Lymphatic surgery for lymphedema occurring either primarily due to an absence or lack of lymphatic vessels or secondarily due to infection, trauma, radiation therapy or surgery can be indicated in specialized microsurgical centers, e.g. for surgical repair of the lymphatic pathway: I) the interrupted lymphatic system can be reconstructed by an interposition, or II) the lymphatic fluid can be drained extraanatomically (e.g. by a lymphatic-venous anastomosis). Further techniques are the following: free lymph node transplantation included in a free vascularized groin flap or autologous lymphatic vessel transfer or vein graft interposition (used for lymphatic vessel interposition). 5) Mass reduction such as dermolipectomy with subsequent split-thickness is a valuable option, which provides excellent volume reduction. 6) Defect coverage: A. Split- or full-thickness skin grafts are a common method of defect coverage (in cases of clean and well-vascularized wound bed and lacking donor skin, or if the graft bed is of questionable quality) using various allogenic or xenogenic skin substitute materials. B. Further methods offer a wide-range armamentarium of local and free fasciocutaneous and musculocutaneous flaps, e.g. after abdomino-perineal rectum extirpation using the vertical rectus-abdominis myocutaneous flap (VRAM) or propeller flaps according to the "angiosome". 7) Abdominal wall hernia closure with instable skin coverage, flap closure, either alone or in combination with mesh is superior to mesh closure only. 8) Free flaps: If there is no option for a local or pedicled flap available, free flaps can be well used for abdominal wall defect closure (complication rate in experienced hands is low). CONCLUSION: Plastic surgery is an indispensable partner for specific surgical problems and clinical situations of general and abdominal surgery, which indicates that each general and abdominal surgeon should be well notified on great options and surgical techniques offered by modern plastic surgery to achieve best outcomes and quality of life for patients and should combine the expertise of these two surgical disciplines.

Apoptosis Induction and Alteration of Cell Adherence in Human Lung Cancer Cells under Simulated Microgravity.

BACKGROUND: Lung cancer cells are known to change proliferation and migration under simulated microgravity. In this study, we sought to evaluate cell adherence, apoptosis, cytoskeleton arrangement, and gene expression under simulated microgravity. METHODS: Human lung cancer cells were exposed to simulated microgravity in a random-positioning machine (RPM). Cell morphology and adherence were observed under phase-contrast microscopy, cytoskeleton staining was performed, apoptosis rate was determined, and changes in gene and protein expression were detected by real-time PCR with western blot confirmation. RESULTS: Three-dimensional (3D)-spheroid formation was observed under simulated microgravity. Cell viability was not impaired. Actin filaments showed a shift in alignment from longitudinal to spherical. Apoptosis rate was significantly increased in the spheroids compared to the control. TP53, CDKN2A, PTEN, and RB1 gene expression was significantly upregulated in the adherent cells under simulated microgravity with an increase in corresponding protein production for p14 and RB1. SOX2 expression was significantly upregulated in the adherent cells, but protein was not. Gene expressions of AKT3, PIK3CA, and NFE2L2 remained unaltered. CONCLUSION: Simulated microgravity induces alteration in cell adherence, increases apoptosis rate, and leads to upregulation of tumor suppressor genes in human lung cancer cells.

Vascular Endothelial Growth Factor Enhances Proliferation of Human Tenocytes and Promotes Tenogenic Gene Expression.

BACKGROUND: In obtaining human tenocytes for tendon tissue engineering, a low proliferation rate and phenotype loss during passaging is a problem. It was the authors' aim to evaluate the influence of vascular endothelial growth factor (VEGF) on human tenocyte growth and gene expression. METHODS: Human tenocytes were exposed to human VEGF in various concentrations (5, 10, and 20 ng/ml) for 5 days. Cell proliferation was counted and expression of tendon-related genes was analyzed. RESULTS: Tenocyte count was 1.4 × 10(5)/ml, 2.7 × 10(5)/ml, 2.3 × 10(5)/ml, and 3.7 × 10(5)/ml for 0, 5, 10, and 20 ng/ml VEGF, respectively. Expression of Col1 was up-regulated 6.4 ± 4.2-fold, 60.1 ± 21.6-fold, and 15.8 ± 10.2-fold for 5, 10, and 20 ng/ml VEGF; all differences were significant with p < 0.05. Col3 was down-regulated to 0.2 ± 0.1-fold, 0.3 ± 0.1-fold, and 0.1 ± 0.03-fold for 5, 10, and 20 ng/ml VEGF; all differences were significant. Eln was up-regulated 2.3 ± 1.7-fold, 25.5 ± 10.9-fold, and 16.6 ± 9.0-fold for 5, 10, and 20 ng/ml VEGF; differences were significant for 10 and 20 ng/ml VEGF. TSC was down-regulated to 0.3 ± 0.1-fold and 0.3 ± 0.1-fold for 5 and 20 ng/ml VEGF; differences were significant for 5 and 20 ng/ml. SCX was up-regulated to 31.3 ± 8.5-fold, 49.1 ± 23.4-fold, and 20.9 ± 9.5-fold for 5, 10, and 20 ng/ml VEGF; all changes were significant. CONCLUSIONS: VEGF enhances proliferation and expression of tendon-related genes in human tenocytes. It could therefore be a useful addition for tenocyte cultivation.

Surgical teaching at the Medical School Otto-von-Guericke University of Magdeburg - basic conceptual description.

Teaching in surgery, one of the classical big clinical and main disciplines beside internal medicine, needs to be also associated with great attention in regard to a valuable final result at the end of the study of human medicine. In particular, surgery is not only the subject to a large number of lectures it also represents one third (four months) of the compulsory internship (practical year - in German, "Praktisches Jahr") at the end of the study of medicine. Therefore, medical teaching of students should be always part of serious and steady attempts to optimize course und contents as a component of guiding activities focussing onto the substantial improvement of the study of medicine. In detail, the classical and traditionally established type of teaching, the (oral) lecture, has to be further developed and reasonably completed by numerous interactive and practice-oriented teaching, learning and examining modalities (obligatory or facultative seminars / courses, training in [very] small groups of students, bed-side teaching, individual practical exercises within the SkillsLab, groups of young researchers, research projects in teaching, scientific publications on topics and recommendable experiences ot teaching including students, "Teach-the-teacher" projects etc.). Although many novel concepts have been inaugurated and considerable advances have been achieved, there is a steady need for further improvement. In the presented representative but medical school-specific overview, the current complex surgical teaching concept, which has been continuously optimized over the last couple of years, at the Otto-von-Guericke University Medical School with University Hospital of Magdeburg (Germany) is described as a scientific and systematizing document as well as a manuscript associated with the ongoing preparation of an institutional "Teaching Manual" on surgical teaching and training for medical students. It should - last but not least - provide the basis for a public discussion, which vice versa might hopefully and possibly result in further structural reforms of (surgical) teaching in the near future.

Spheroid formation and modulation of tenocyte-specific gene expression under simulated microgravity.

BACKGROUND: For tendon tissue engineering, tenocyte-seeded scaffolds are a promising approach. Under conventional 2D culture however, tenocytes show rapid senescene and phenotype loss. We hypothesized that phenotype loss could be counteracted by simulated microgravity conditions. METHODS: Human tenocytes were exposed to microgravity for 9 days on a Random Positioning Machine (RPM). Formation of 3D-structures (spheroids) was observed under light microscopy, gene expression was measured by real-time PCR. Cells under conventional 2D-culture served as control group. RESULTS: Simulated microgravity reached a value of as low as 0.003g. Spheroid formation was observed after 4 days, and spheroids showed stable existance to the end of the observation period. After 9 days, spheroids showed a significantly higher gene expression of collagen 1 (Col1A1) compared to adherent cells under microgravity (4.4x, p=0.04) and compared to the control group (5.6x, p=0.02). Gene expression of collagen 3 (COL3A1) was significantly increased in spheroids compared to the control group (2.3x, p=0.03). Gene expressions of the extracellular matrix genes Tenascin C und Fibronectin (TNC and FN) were increased in adherent cells under microgravity compared to the 1g-control group, not reaching statistical significance (p=0.1 and p=0.3). For the gene expression of vimentin, no significant alteration was observed both in the adherent cells and in the spheroids compared to the 1g control group. Gene expression of the tenocyte-specific transcription factor scleraxis (SCX) was significantly increased in spheroids compared to the control group (3.7x, p=0.03). CONCLUSION: Simulated microgravity could counteract tenocyte senescence in vitro and serve as a promising model for scaffold-free 3D cell culturing and tissue engineering. LEVEL OF EVIDENCE: V (laboratory study).

Flexor Tendon Sheath Engineering Using Decellularized Porcine Pericardium.

BACKGROUND: The flexor tendon sheath is an ideal target for tissue engineering because it is difficult to reconstruct by conventional surgical methods. The authors hypothesized that decellularized porcine pericardium can be used as a scaffold for engineering a biologically active tendon sheath. METHODS: The authors' protocol removed cellular material from the pericardium and preserved the structural architecture in addition to the collagen and glycosaminoglycan content. The scaffold was successfully reseeded with human sheath synoviocytes and human adipose-derived stem cells. Cells were evaluated for 8 weeks after reseeding. RESULTS: The reseeded construct demonstrated continuous production of hyaluronic acid, the main component of synovial fluid. After being seeded on the membrane, adipose-derived stem cells demonstrated down-regulation of collagen I and III and up-regulation of hyaluronan synthase 2. CONCLUSION: The results indicate that decellularized porcine pericardium may be a potential scaffold for engineering a biologically active human tendon sheath.

Aggressive digital papillary adenocarcinoma - a rare malignant tumor of the sweat glands: two case reports and a review of the literature.

Aggressive digital papillary adenocarcinomas are rare malignant tumors often located on the digits of the hand. Due to lack of pain, slow growth, and an inconspicuous appearance, diagnosis is often missed or delayed. We report two cases and review the present literature to give recommendations for diagnosis and treatment.

Genital Reconstruction After Weight Loss in Adipose Male Patients: A Case report.

OBJECTIVE: We introduce our surgical technique in two male genital reconstruction cases out of 15 post-bariatric patients. METHODS: At our Department for Plastic Surgery at the University Hospital Magdeburg, 15 patients, 6 male and 9 female, underwent a surgical abdominoplasty after weight loss in 2009. RESULTS: The average weight of the 15 patients was preoperatively 197.2 kg and the average hospital stay was of 14 days. In 2 cases, a second procedure for male genital reconstruction was necessary. After primary dietary measures and weight loss, we performed genital reconstruction in a second step with a sleeve-, Z-, VY-plasty and a "bilobed flap" to restore function and appearance of the male genitalia. In these patients, the average weight was 207.5 kg and hospital stay lasted 32 days. CONCLUSION: The increase of patients with obesity-related genital deformities will be expected in the future. Therefore, more controlled long-term studies should be published to develop guidelines for genital reconstruction techniques in plastic surgery.

Minimally invasive endoscopic decompression for anterior interosseous nerve syndrome: technical notes.

Anterior interosseous nerve syndrome (Nevin-Kiloh syndrome) is a rare entity caused by compression of the purely motor anterior interosseous nerve in the forearm. Historically, conventional surgical treatment has consisted of open decompression of the nerve. Unfortunately, open decompression is often complicated by scarring and significant morbidity. Endoscopic decompression is an alternative means of surgical intervention in the hands of well-trained surgeons comfortable with soft tissue endoscopy. In this report, we review relevant anatomy, offer technical hints, and present our personal experience with 4 illustrative cases, all with greater than 1.5 years of follow-up. Our patients showed considerable improvement of their symptoms with minimal scarring. No significant complications occurred.

Co-culture of human adipose-derived stem cells with tenocytes increases proliferation and induces differentiation into a tenogenic lineage.

BACKGROUND: Seeding acellularized tendons with cells is an approach for creating tissue-engineered tendon grafts with favorable biomechanical properties. It was the authors' aim to evaluate whether human adipose-derived stem cells could replace tenocytes for scaffold seeding. METHODS: Adipose-derived stem cells and tenocytes were co-cultured in different ratios (3:1, 1:1, and 1:3) and with three different methods: (1) direct co-culture, (2) tenocyte-conditioned media on adipose-derived stem cells, and (3) an insert system to keep both cell types in the same media without contact. Proliferation, collagen production, and tenogenic marker expression were measured by hematocytometry, immunocytochemistry, enzyme-linked immunosorbent assay, and real-time polymerase chain reaction. RESULTS: Proliferation and collagen production were similar for tenocytes and adipose-derived stem cells alone. Phenotype difference between adipose-derived stem cells and tenocytes was indicated by higher tenascin C and scleraxis expression in tenocytes. Proliferation was increased in direct co-cultures, especially at an adipose-derived stem cells-to-tenocyte ratio of 3:1, and for tenocytes in adipose-derived stem cell-conditioned media. Direct co-culture caused significant up-regulation in tenascin C expression in adipose-derived stem cells (4.0-fold; p<005). In tenocyte-conditioned media, tenascin C expression was up-regulated 2.5-fold (p<0.05). In the insert system, tenascin C expression was up-regulated 2.3-fold (p<0.05). CONCLUSIONS: Adipose-derived stem cells are good candidates for tendon tissue engineering because they are similar to tenocytes in proliferation and collagen production. With an optimal ratio of 3:1, they increase proliferation in co-culture and change their phenotype toward a tenogenic direction.