Evan S. Garfein

Engineering vascularized skeletal muscle tissue

One of the major obstacles in engineering thick, complex tissues such as muscle is the need to vascularize the tissue in vitro. Vascularization in vitro could maintain cell viability during tissue growth, induce structural organization and promote vascularization upon implantation. Here we describe the induction of endothelial vessel networks in engineered skeletal muscle tissue constructs using a three-dimensional multiculture system consisting of myoblasts, embryonic fibroblasts and endothelial cells coseeded on highly porous, biodegradable polymer scaffolds. Analysis of the conditions for induction and stabilization of the vessels in vitro showed that addition of embryonic fibroblasts increased the levels of vascular endothelial growth factor expression in the construct and promoted formation and stabilization of the endothelial vessels. We studied the survival and vascularization of the engineered muscle implants in vivo in three different models. Prevascularization improved the vascularization, blood perfusion and survival of the muscle tissue constructs after transplantation.

Clinical applications of tissue engineered constructs

The reconstruction of soft tissue defects poses a challenge for plastic surgeons and tissue engineers. The construction of a biologically, functionally, and cosmetically successful replacement part will involve the combination of a composite that contains endoderm, mesoderm, and ectoderm. It will be active in immune surveillance and function. It must be durable to withstand the stress and strain encountered by the skin. Such a composite will involve the use of bone, cartilage, muscle, blood vessels, nerves, connective tissue, dermis, and epidermis. Fortunately, many of these tissues are among the best studied by tissue engineers. The future of this field will likely involve to some degree the co-mingling of current reconstructive modalities, including the techniques of prefabrication and pre-lamination, with more aggressive and successful tissue engineering technology and the rapidly developing science of stem cell biology. Tissues synthesized in vitro with better structure, color, and texture can be pre-laminated to a site that has already been prefabricated. Prefabrication of a bio-absorbable matrix can create a well perfused scaffold onto which larger subunits can be prelaminated. The future of this field of endeavor is exciting, and, with further research, experience, and interdisciplinary collaboration, bioengineered tissue constructs will become a reality.

The vertical and extended rectus abdominis myocutaneous flap for irradiated thigh and groin defects.

Background: Thigh and groin tumors are often treated with limb-sparing surgery and adjuvant preoperative irradiation, frequently resulting in complex soft-tissue defects and wounds. The authors evaluated outcomes after reconstruction of these difficult wounds with the vertical and extended rectus abdominis myocutaneous (RAM) flap. Methods: A retrospective chart review was performed of 50 consecutive patients who underwent inferiorly based RAM pedicle flaps to reconstruct thigh and groin defects after preoperative irradiation and oncologic resection. Timing of reconstruction, flap design, complications, metastasis/recurrence, and ambulation status were analyzed. Results: Fifty patients (mean age, 56 years; range, 10 to 83 years) underwent 51 RAM flaps. Sixty-three percent of flaps were for immediate reconstruction and the remaining flaps were for secondary coverage after failure of initial closure. There were no perioperative deaths. The median length of hospital stay was 9 days. All flaps survived. The vertical RAM flap was used in 63 percent of cases; the extended RAM flap was used in 37 percent and permitted closure of larger, contralateral, and more distal defects. With a mean follow-up of 28 months, complications included partial flap necrosis [n = 2 (4 percent)], infection [n = 8 (16 percent)], seroma [n = 2 (4 percent)], dehiscence [n = 2 (4 percent)], and donor-site bulge [n = 6 (12 percent)]. Postoperative wound complications were significantly higher in patients who underwent delayed or secondary (47 percent) versus immediate reconstruction (9.4 percent, p < 0.005). Three patients required additional coverage. There was no significant difference in flap complications between the extended and nonextended flap designs. Independent ambulation was achieved in 82 percent of patients. Conclusions: The vertical and extended RAM flaps provide reliable coverage of irradiated thigh and groin oncologic wounds, with significantly improved results obtained with immediate versus delayed reconstruction.

Learning from a lymphedema clinic: an algorithm for the management of localized swelling.

Background: Lymphedema is a chronic disease causing significant morbidity for affected patients. It can be difficult to diagnose, and patients are often frustrated by multiple referrals and inadequate therapies. Centralized, comprehensive care for the patient presenting with lymphedema or other causes of localized swelling allows for appropriate evaluation and provides improved management and treatment. Methods: A 4-year review of the first 100 patients seen at the Beth Israel Deaconess Medical Center Lymphedema Clinic was performed. On the basis of the clinical experience from these patients, an algorithm for diagnosing and managing patients with localized swelling was developed. Results: The mean age of the patients was 50 years, and 81 percent of the patients were women. On average, patients had experienced their symptoms for 11.6 years (range, 3 months to 60 years). Lymphoscintigraphy was performed on 43 patients, 81 percent of whom showed lymphatic obstruction or dysfunction. In total, 75 percent of patients were diagnosed with lymphedema based on clinical presentation or additional testing. Fourteen of these patients underwent subsequent excisional procedures, whereas the rest were managed conservatively with compression garments. Conclusions: Patients presenting with swollen extremities can frequently be diagnosed through history and physical examination alone, but many patients require more extensive diagnostic workup. An algorithm for the management of these patients can facilitate evaluation and treatment.

The new age of three-dimensional virtual surgical planning in reconstructive plastic surgery.

free-fibula reconstruction of the mandible.4 Three-dimensional comparisons demonstrated a mean overlap of 59 percent, with minimal deviation from the planned reconstruction. This type of analysis is essential as this technology evolves, as is the study of other important parameters such as operative time and total cost. We hope this discussion adds to the ongoing work by various physicians worldwide using virtual planning in reconstruction of the jaw. We look forward to other exciting reports from such groups and await critical review of this technology in years to come. DOI: 10.1097/PRS.0b013e318254fbf6

Side population hematopoietic stem cells promote wound healing in diabetic mice

Background: Early evidence suggests that stem cells play a role in normal wound healing. Various impaired wound-healing states might be due to a deficiency in the stem cell repertoire. The authors sought to demonstrate that a new subset of lymphoid progenitor murine hematopoietic stem cells will accelerate wound healing in diabetic mice. Methods: Bone marrow cells were harvested from C57Bl6/J femurs and separated into side and main populations based on their ability to efflux the vital dye Hoechst 33342 and the presence or absence of CD7 and CD34 markers. Side or main population cells and control solution were applied once topically to 1-cm2 full-thickness dorsal excisional wounds in lepr db/db and wild-type mice on the day after wounding (n = 12 in each group). Wound closure was followed by computer planimetry. Wounds were harvested after 7 and 25 days for histological analysis. Results: Topical side population treatment had a significant effect on wound closure in diabetic animals, with a higher percentage of wound closure (35 ± 7.2 percent) in this group on postoperative day 7 compared with animals treated with either main population cells (16 ± 4.9 percent) or a vehicle control using saline (14 ± 6.7 percent) (p < 0.05). When side population cells were given to wild-type mice that already had a normal stem cell repertoire, there was a trend toward better wound closure, but no significant differences were found. Conclusions: Side population–treated wounds healed more quickly than main population–or control-treated wounds in diabetic mice, suggesting that one stem cell subpopulation, but not the majority, harbors the potential for improving the healing process. Further studies are needed to investigate the mechanism of healing and to explore its potential as a therapeutic agent.

The privilege of advocacy: legislating awareness of breast reconstruction.

In 2010, New York State passed legislation sponsored by Assemblywoman Naomi Rivera and State Senator Ruth Hassel-Thompson that mandates hospitals and physicians inform women of the option of breast reconstruction after mastectomy. Authoring this legislation was surprisingly educational and simple. It can easily be replicated in the other 49 states with the help of readers of this Journal. From the pioneering days of breast reconstruction with silicone implants in the 1960s to the autologous era beginning with Hartrampf in the 1980s, to the more elaborate and nuanced techniques of today, plastic surgeons have successfully developed a set of operations that provide women with a wide variety of options for reconstructing the postmastectomy defect.1 Today, among the dozen accepted techniques, most women can find a procedure that will be deemed a success, in their eyes and in their surgeon’s eyes. Among women undergoing mastectomy, a minority undergo reconstruction. Some women choose not to undergo reconstruction. Some are not candidates because of advanced disease, comorbid conditions, or advanced age. Some do not know that reconstruction exists as an option and are never educated otherwise. Some women think reconstruction is viewed as cosmetic by their insurance companies and are unable to afford it. Some would choose it but are not referred to a plastic surgeon. The first two factors are beyond our control. The last three are not. There are two issues to address: the overall low rate of reconstruction and the much lower rate of reconstruction among poor and minority women in the United States. In 1998, Senator D’Amato of New York authored federal legislation entitled the Women’s Health and Cancer Rights Act to address both issues. Among other things, it guaranteed universal coverage for women undergoing breast reconstruction for postmastectomy or postlumpectomy defects. In the first decade following passage of this bill, several large studies examined the disparities in rates of reconstruction among various socioeconomic and racial groups. Guaranteeing universal coverage for reconstruction should have had a major impact on the overall rate of reconstruction and on the existent disparity. Unfortunately, it did not. Several investigators have analyzed why the elimination of financial barriers has played little role in making breast reconstruction more accessible. In 2004, Tseng et al. found that African American women were 34 percent as likely to undergo immediate reconstruction as white women.2 In 2005, Joslyn reported the low overall rate of immediate reconstruction among the studied cohort (approximately 20 percent of women undergoing mastectomy) and the 40 percent decrease, after multivariate analysis, in the likelihood that black women will undergo immediate or early reconstruction compared with white women.3 Alderman et al. also used the National Cancer Institute’s Surveillance, Epidemiology and End Results database to examine the use of immediate and early breast reconstruction. They found a 15 percent immediate/early reconstruction rate overall, a widely disparate rate based on geographic region, and significant disparities based both on age and on race.4 Greenberg et al. noted that the single greatest predictor of whether a woman underwent breast reconstruction was the mentioning of reconstruction by the breast surgeon in the initial consultation.5 In an effort to further understand why such significant disparities persist, Alderman et al. explored referral patterns from breast surgeons to plastic surgeons. They found that only 24 percent of breast surgeons in metropolitan Detroit and From the Division of Plastic Surgery, Montefiore Medical Center. Received for publication February 3, 2011; accepted February 9, 2011. Copyright ©2011 by the American Society of Plastic Surgeons

First Evidence that Bone Marrow Cells Contribute to the Construction of Tissue Engineered Vascular Autografts In Vivo

The authors designed and tested a bone marrow cell-seeded biodegradable scaffold to repair cardiac defects that avoids the problems of unwanted adverse effects and lack of growth potential. After being labeled with green fluorescence, bone marrow cells were seeded onto scaffolds and implanted in the inferior vena cava of dogs. After implantation, the grafts were analyzed by using antibodies against endothelial cell lineage markers, endothelium and smooth muscle cells at 3 hours, and then at 2, 4, and 8 weeks. The tissue-engineered vascular autographs caused no obstruction or stenosis. The seeded bone marrow cells expressed endothelial cell lineage markers that were adhered to the scaffold. Proliferation and differentiation followed and resulted in the expression of smooth muscle cell markers and endothelial cell markers, vascular endothelial growth factor and angiopoietin-1. The study results provide evidence that bone marrow cells enable the establishment of tissue-engineered vascular autographs.