The cellular plasticity of human adipocytes.

Little is known regarding the biology of fat considering its extensive use clinically in soft tissue implantation. Free-fat transfer is problematic the result of graft site volume loss, appearing histologically as the replacement of mature adipocytes with a fibroblast-like infiltrate. We hypothesize that these histologic changes reflect a dedifferentiation of ischemic mature adipocytes instead of, or in addition to, a more traditional response. To explore this hypothesis, we studied the in vitro morphologic changes of cultured mature human adipocytes isolated from liposuctioned adipose tissue. Most adipocytes over time lost significant amounts of intracellular lipid. Ultimately, these cells lost all lipid, appeared fibroblastic, and proliferated to confluence. Adipogenic induction of such dedifferentiated adipocytes resulted in reaccumulation of intracellular lipid. This study demonstrates that mature adipocytes can be cultured from human liposuctioned fat, they can dedifferentiate into fibroblastic cells, and the fibroblast-like cells can be expanded and turned into lipid-synthesizing adipocytes. Exploration of this cellular plasticity might ultimately yield important insights into free-fat transfer and novel tissue-engineering strategies.

Multilineage cells from human adipose tissue: implications for cell-based therapies.

Future cell-based therapies such as tissue engineering will benefit from a source of autologous pluripotent stem cells. For mesodermal tissue engineering, one such source of cells is the bone marrow stroma. The bone marrow compartment contains several cell populations, including mesenchymal stem cells (MSCs) that are capable of differentiating into adipogenic, osteogenic, chondrogenic, and myogenic cells. However, autologous bone marrow procurement has potential limitations. An alternate source of autologous adult stem cells that is obtainable in large quantities, under local anesthesia, with minimal discomfort would be advantageous. In this study, we determined if a population of stem cells could be isolated from human adipose tissue. Human adipose tissue, obtained by suction-assisted lipectomy (i.e., liposuction), was processed to obtain a fibroblast-like population of cells or a processed lipoaspirate (PLA). These PLA cells can be maintained in vitro for extended periods with stable population doubling and low levels of senescence. Immunofluorescence and flow cytometry show that the majority of PLA cells are of mesodermal or mesenchymal origin with low levels of contaminating pericytes, endothelial cells, and smooth muscle cells. Finally, PLA cells differentiate in vitro into adipogenic, chondrogenic, myogenic, and osteogenic cells in the presence of lineage-specific induction factors. In conclusion, the data support the hypothesis that a human lipoaspirate contains multipotent cells and may represent an alternative stem cell source to bone marrow-derived MSCs.

A novel device for the simple and efficient refinement of liposuctioned tissue.

In short, our device allows a surgeon who is harvesting adipose tissue for autologous fat transplantation to immediately, easily, efficiently, and sterilely isolate adipose tissue from the unwanted waste components that are associated with primary liposuction effluent. It does so by "trapping" the fat tissue contained within raw liposuction effluent. Once the tissue fraction has been separated, the device design then allows for direct implantation or subsequent washing/rinsing of the tissue with saline/buffer of choice in preparation for tissue reimplantation.

Emerging approaches to the tissue engineering of fat.

The eventual development of tissue-engineered fat equivalents for reconstructive and augmentation purposes will be most welcome by nearly every surgical discipline and prove to be especially useful for plastic surgeons. The clinical applications for which tissue-engineered fat will be particularly useful are vast and varied and can be loosely categorized into reconstructive, cosmetic, corrective, and orthotic indications. In this article, the authors discuss the emerging tissue-engineering strategies for fat, including the procurement of autologous cells, cell growth and differentiation, implantation and engraftment, polymer scaffolds, and implant integration and histogenesis.

Preoperative cooling and warming of the donor site increase survival of skin flaps by the mechanism of ischaemic preconditioning: an experimental study in rats.

Recent studies show that survival of skin flaps can be increased by ischaemic preconditioning with repeated cycles of ischaemia and reperfusion before prolonged ischaemia or raising of the flap. In this study three cycles of cooling and warming of rat dorsal skin were used to regulate skin blood flow and to induce three cycles of ischaemia and reperfusion. In 10 Sprague-Dawley rats three cycles of cooling (-18 degrees C ice pack) and warming (45 degrees C running water) were used to regulate skin blood flow before the flaps were raised. Caudally-based skin flaps 11 x 2 cm were then raised to the left of the dorsal midline and sutured back. In the control group (n = 9) the flap was raised and sutured back without any treatment. Viability was assessed after seven days and the survival area calculated with planimetry. Viability increased from a mean (SD) of 61 (6)% in the control group to 77 (7)% in the experimental group (p < 0.0001). This study shows that preoperative cooling and warming of the donor site can be used to increase survival of skin flaps. The probable explanation is ischaemic preconditioning although the biochemical mechanism is unclear.

The Charles procedure: misquoted and misunderstood since 1950.

The Charles procedure, named for Sir Richard Henry Havelock Charles, is an eponym for a surgical treatment of leg lymphedema. Sir Havelock led a fascinating life, with his travels taking him to India, the Afghan territories, and the Court of King George V of England. At the turn of this century, Sir Havelock published material describing a series of 140 consecutive patients treated successfully for scrotal lymphedema. In a book chapter published a decade later, entitled "Elephantiasis Scroti," Sir Havelock briefly described the treatment of leg lymphedema but did not document a single successful case report. The name of Sir Havelock Charles was absent from the literature until 1950, when Sir Archibald McIndoe attributed the treatment of leg lymphedema with radical excision and skin grafting to Sir Havelock. References to Charles for the treatment of leg lymphedema have proliferated since that time.

Scrotal elephantiasis associated with hidradenitis suppurativa.

Hidradenitis suppurativa is a chronic relapsing infection of the apocrine sweat glands. Its association with penoscrotal lymphedema is not well recognized. A case of massive scrotal elephantiasis associated with chronic hidradenitis of the perineum and scrotum is described. A wide resection of the scrotal mass and perineum was performed, with reconstruction of the perineum and penis carried out using local skin flaps and split-thickness skin grafts. This one-stage treatment yielded an excellent cosmetic and functional outcome.

Radical excision and delayed reconstruction of a lymphedematous leg with a 15 year follow-up.

An adult female patient with primary lymphedema of the lower extremity was treated with total excision of the subcutaneous tissues followed by delayed reconstruction with a giant full thickness skin graft taken from the excised surgical specimen. The leg has maintained excellent function and contour over the ensuing 15 years. A small area on the dorsum of the foot that initially was covered with a split thickness skin graft required subsequent regrafting using abdominal skin. This area developed verrucoid changes.

Comparative clinical study of the sure-closure device with conventional wound closure techniques.

The Sure-Closure device, designed for wound closure, harnesses the viscoelastic properties of the skin. It has been used in clinical studies in the past. We have evaluated the role of this device in complex wound problems and compared it to closure achieved by conventional wound closure methods such as skin grafts and flaps. A total of 40 patients with multiple wound etiologies were examined. We used the device under local and general anesthesia. In addition, we performed cost analysis on the use of the device and compared this to traditional methods. We found a cost reduction trend associated with the Sure-Closure method (p < .05). All of the 24 patients in whom the device was used to close the wounds had complete primary closure. The device is also easy to use. When used for delayed stretching, as in some of our patients, the compliance rate was high.

Variations in the vascular pedicle of the rat gracilis muscle flap.

The rat gracilis muscle is a reliable model for microsurgical research. Exploration of 364 inguinal regions and preparation of 80 free gracilis muscle flaps in Sprague-Dawley and Lewis rats revealed six distinct origins of the dominant arterial pedicle and four variations of the venous pedicle. Popliteal, external iliac, and truncus pudendoepigastricus associations are described for the first time in this study. The total incidence of atypical variation of arterial pedicle origin is 20.7 percent. The most common origin of muscular branch arteries are the superficial epigastric artery (53.3 percent), femoral artery (22.0 percent), popliteal artery (14.6 percent), and the external iliac arteries (5.5 percent). Muscular branch veins drain most frequently into the femoral vein (79.1 percent). Gracilis muscle flaps prepared from rats weighing 329 +/- 45 g weighed an average of 0.64 +/- 0.13 g, and their volume averaged 0.87 +/- 0.12 ml. Muscular branch artery and vein diameters (external) averaged 0.21 +/- 0.05 mm and 0.54 +/- 0.06 mm, respectively. This new anatomic information is essential for reproducible microsurgery research using the rat gracilis muscle.

Preparation of viable tumour cell vaccine from human solid tumours: relationship between tumour mass and cell yield. The Tissue Bank, Pittsburgh Cancer Institute.

Active specific immunotherapy for cancer often requires the use of autologous or allogeneic tumour cells as immunizing antigen. Tumours were obtained for such a protocol. However, estimation of viable cell yield from pre-processed fresh tumour mass was difficult, and initially there did not appear to be a direct relationship between pre-processed tumour mass and viable cells obtained after processing. We therefore analysed all of 293 tumour specimens processed to attempt to discern such a relationship. Of these 137 were melanoma, 14 were sarcoma, 48 were adenocarcinoma, 59 were renal cell carcinoma and 35 were classified as other. A positive correlation was found between pre-processed tumour mass and viable cell yield, with Spearman correlation values varying from r = 0.49 (adenocarcinoma) to r = 0.84 (melanoma). For all tumours the Spearman correlation was r = 0.70 (p = 0.0001). Not surprisingly, the most frequent site of removal associated with bacterial contamination was bowel. In conclusion, this study provides useful curves for predicting viable tumour cell yield from pre-processed tumour mass of given histology.

Combined tissue expansion and free tissue transfer for reconstruction of the hand in epidermolysis bullosa-associated malignancy.

The recessive form of dystrophic epidermolysis bullosa (RDEB) is associated with severe hand deformities characterized by cocooning pseudopolysyndactyly, recurrent ulceration, fibrosis, and adduction contracture of the thumb. In addition, RDEB is associated with an aggressive form of squamous carcinoma, notable for rapid metastases, appearance at an early age, and a relative resistance to radiation or chemotherapy. To date, reported reconstructive treatment has been limited to excision with skin grafting or amputation. We report the successful combined use of tissue expansion and microsurgical free tissue transplantation to reconstruct a patient with RDEB found to have malignancy of the hand. Donor skin was found to expand without blistering, and use of the expander allowed primary donor site closure after microsurgical transplantation of a scapular flap. We recommend wide tumor resection and the aggressive use of contemporary reconstructive methods to maintain hand function and associated quality of life in patients with RDEB who develop malignancy.

Histomorphologic changes in expanded skeletal muscle in rats.

Tissue expansion is one of the powerful tools for various reconstructive procedures and has proven to provide more available local tissues. However, limited attention has been given to the characteristics of expanded skeletal muscle. Using a rat model (n = 41), we expanded the rat gracilis muscle and investigated the histomorphologic changes in the expanded skeletal muscle. By expansion, the gracilis muscle after 3 weeks increased 50.4 to 58.4 percent in length and 60.5 percent in width and decreased 39.0 to 42.0 percent in thickness. Histologically, the expanded muscle demonstrated a normal striation and no signs of inflammation or necrosis. The cross-sectional areas of muscle fibers indicated that expanded muscle consisted of predominantly smaller fibers. Vasculature in the expanded muscle demonstrated a longer network of arteries and a more obvious and developed arterial arcade. The average number of sarcomeres in a fiber estimated from the sarcomere length and fiber length was significantly greater (46.5 percent) in the expanded muscle. These findings suggest that the expansion of skeletal muscle is not a "stretching" process of muscle but rather a growth process of the muscle accompanied by an increase in the number of sarcomeres per fiber. Furthermore, the expanded skeletal muscle appears to preserve normal skeletal muscle architecture, vasculature, and function while undergoing the ischemic stress of expansion.

Laser-assisted microvascular anastomosis of human adult and placental arteries with expanded polytetrafluoroethylene microconduit.

Laser-assisted microvascular anastomoses can be performed more quickly than sutured anastomoses, yet manifest similar patency rates and tensile strength. This study was undertaken to determine if in vitro laser-assisted microvascular anastomoses could be created between human adult arteries (anterior tibial arteries), human placental arteries, and expanded polytetrafluoroethylene microconduits. A CO2 laser was applied in single or continuous bursts with a matrix of variables encompassing power P = 80 to 160 mW, spot size SS = 150 to 500 microns, and exposure time EXP = 1.0-second continuous exposure (n = 2 each composite setting). The endpoints measured to assess the ability to laser-weld vessels were morphologic appearance by scanning electron microscopy and bursting strength. Scanning electron microscopy revealed apparent fusion of human placental arteries and human adult arteries to expanded polytetrafluoroethylene microconduits at settings of P = 130 mW, SS = 300 microns, and EXP = 1.0 second, though bursting pressure at all settings was less than 10 mmHg. Laser-assisted microvascular anastomoses of human placental artery to human placental artery and human adult artery to human adult artery were successful at this setting, though bursting pressures of anastomoses incorporating placental vessels were significantly weaker than those created with adult tissue. The relative weakness of laser-assisted microvascular anastomoses incorporating placental arteries might be explained by qualitative or quantitative differences in vessel wall collagen, as seen in fetal tissue, and deserves further characterization.

Improved chest wall fixation for correction of pectus excavatum.

Pectus excavatum, the most common congenital chest wall abnormality, is manifested by deformity of the costal cartilages resulting in a depressed and often rotated sternum. Although there are conflicting data to support and reject the concept that physiologic improvement can be a consequence of surgical repair, correction is frequently indicated for aesthetic improvement alone. The most popular current repair involves resection of abnormal costal cartilages, sternal osteotomy and mobilisation, followed by fixation of the sternum in the corrected position. Improved fixation techniques have evolved, but generally have not employed current concepts of rigid fixation. The correction of pectus excavatum using reconstruction plates incorporates the benefits of rigid fixation, while allowing custom chest wall contouring and sternal reorientation. Reconstruction plate fixation of the sternum should be considered during correction of pectus excavatum in adult and adolescent patients.

The buccinator myomucosal island pedicle flap: anatomic study and case report.

The buccinator myomucosal island pedicle flap is a useful means of introducing relatively large amounts of vascularized mucosa into the oral cavity. Using cadaver dissections and clinical cases, the anatomy and clinical relevance of this tissue are defined. Emphasis is placed on the technical caveats and pitfalls of the procedure.

Evaluation of facial fat distribution using magnetic resonance imaging.

Magnetic resonance imaging (MRI) provides noninvasive images of facial and neck fat for a variety of conditions. It accurately maps the soft tissues pre- and postoperatively, enabling surgeons to precisely and objectively assess results of soft tissue facial contouring and fat transplantation. The risks of MRI are few. It has the potential to provide aesthetic surgeons with a more "scientific" means of comparing various techniques of fat contouring.

The influence of tissue expanders on grafted vessels.

Interpositionally grafted arteries and veins were expanded with a 20cc tissue expanders in 50 Sprague-Dawley rats. The grafts were done on both hind legs, one side was expanded and the remaining side was used as control. The average gain in length of expanded grafted arteries and veins was over 4 and 6 times that of the controls respectively. The differences in the patency rates between expanded and control grafts were not statistically significant. Histologic examination revealed that there were no changes in the areas of the media and lengths of the inner elastic laminae of the expanded arterial grafts. In both expanded and control vein grafts, marked intimal thickening was noticed, although these changes were not statistically significant. Expansion of grafted vessels can be safely carried out without loss of vessel patency.