Latissimus Dorsi Flap Breast Reconstruction-A Nationwide Inpatient Sample Review.

INTRODUCTION: The latissimus dorsi (LD) myocutaneous flap has been a long term standard for breast reconstruction. The variable indications for the LD flap have not been statistically examined because of the relative infrequency of its use by any single surgeon or institution. METHODS: The Nationwide Inpatient Sample data set was queried for all patient encounters involving a LD myocutaneous flap procedure. The study population was further restricted to female patients with a history of breast cancer or previous mastectomy. Demographics, Charlson Comorbidity Index scores, previous radiation history, and additional simultaneous procedures were extracted. Analysis was performed using nonparametric correlation coefficients and linear regression models. RESULTS: In total, 2304 LD breast reconstruction hospitalizations were identified between 2008 and 2010. Average patient age was 52.1 years, average hospital length of stay (LOS) was 2.8 days, bilateral latissimus reconstruction was performed in 252 (10.9%) patients, and 1414 patients (61.4%) were delayed reconstruction. Previous irradiation was present in 389 (16.9%) patients and was correlated with delayed reconstruction (P < 0.001).Younger age was associated with bilateral latissimus reconstructions (P < 0.05), contralateral free flap reconstruction (P < 0.0001), and combination with implants or tissue expanders (both P < 0.0001).After adjustment for age and Charlson Comorbidity Index, increased LOS was observed in patients undergoing contralateral free flap reconstruction (+1.29 days, P < 0.05) and immediate reconstruction (mastectomy, +0.39 days unilateral, P < 0.05; +0.64 days, bilateral, P < 0.001). The use of tissue expanders and implants were found to decrease hospital LOS (bilateral implant, -0.65 days, P < 0.001; bilateral expander, -0.72 days, P < 0.001), likely from confounding comorbidities. Charlson Comorbidity Index was strongly related to LOS (+0.08 days per point, P < 0.005), whereas age was not statistically significant when considered with comorbidity. CONCLUSIONS: The LD is most commonly used for delayed or salvage breast reconstruction, with particular utility in irradiated patients. Younger patients tend to undergo more involved LD variants with bilateral reconstructions and expanders or implants. After adjusting for comorbidity, age and the use of bilateral latissimus flaps with implants or expanders have no adverse impact on LOS.

Gender-Affirming Mastectomy: Psychosocial and Surgical Outcomes in Transgender Adults.

BACKGROUND: Limited literature exists examining the effects of gender-affirming mastectomy on transmasculine and nonbinary patients that is prospective and uses validated survey instruments. STUDY DESIGN: The psychosocial functioning of transmasculine and nonbinary patients was compared between patients who underwent gender-affirming mastectomy and those who had not yet undergone surgery. Participants were enrolled in a single-site, combined study of surgical and psychosocial outcomes, including a cross-sectional cohort of preoperative and postoperative patients, as well as separate prospective cohort. Participants completed the BREAST-Q psychosocial and sexual well-being modules, the BODY-Q satisfaction with chest and nipples modules, the Body Image Quality of Life Inventory, the Transgender Congruence Scale, the Patient Health Questionnaire-9, and the Generalized Anxiety Disorder-7 scale before and after surgery. We also examined how patient demographic factors correlated with postoperative surgical and psychosocial outcomes. RESULTS: A total of 111 transmasculine and nonbinary patients 18 to 63 years of age (mean ± SD 26.5 ± 8) underwent mastectomy and were included in the study. All were included in the cross-sectional cohort, and 20 were enrolled in the prospective cohort. More than one-third (34.2%) of patients were nonbinary. After surgery, psychosocial and sexual well-being, satisfaction, body image-related quality of life, and gender congruence were increased (p < 0.001) in both cohorts, and depression (p < 0.009 cross-sectional), and anxiety (p < 0.001 cross-sectional) were decreased. The most common adverse event was hypertrophic scarring, which occurred in 41 (36.9%) participants. CONCLUSIONS: In this study of transmasculine and nonbinary adults, gender-affirming mastectomy was followed by substantial improvements in psychosocial functioning.

Chest wall reconstruction for sternal dehiscence after open heart surgery.

BACKGROUND: Sternal dehiscence is a grave complication after open heart surgery. Sternal debridement and flap coverage are the mainstays of therapy, but no consensus exists regarding the appropriate level of debridement. More recently, the use of vacuum-assisted closure devices has been advocated as a bridge to definitive closure, but indications for use remain incompletely defined. MATERIALS AND METHODS: A retrospective review of all chest wall reconstructions performed from January 2000 to December 2010 was conducted. The type of operative management was evaluated to assess morbidity, mortality, and length of hospital stay. RESULTS: Fifty-four patients underwent chest wall reconstruction for poststernotomy mediastinitis. Of these patients, 24 underwent conservative sternal debridement with flap closure, 24 underwent radical sternectomy including resection of the costal cartilages followed by flap closure, and 6 underwent radical sternectomy with vacuum-assisted closure therapy followed by flap closure in a delayed fashion. There were 15 patients in the conservative group and 8 patients in the radical sternectomy group who developed postoperative complications (62.5% vs 33.3%, P < 0.05). The conservative sternectomy group had more serious complications requiring reoperation compared to the radical sternectomy group (86.7% vs 25.0%, P < 0.05). The most common complication in the former group was flap dehiscence (8/15, 53.3%), whereas that in the latter group was a superficial wound infection (6/8, 75.0%). There was no significant difference in mortality (25.0% vs 25.0%, P > 0.05%) or length of hospital stay. CONCLUSIONS: Radical sternectomy including the costal cartilages is associated with lower rates of surgical morbidity and reoperation, but not mortality.

Mohs versus surgical excision in nonmelanoma skin cancers: does location matter?

INTRODUCTION: Every year, nearly 1.2 million people are affected by nonmelanoma skin cancers (NMSCs) in the United States. Most published data focus on comparing the efficacy of Mohs micrographic surgery (MMS) versus traditional surgical excision (TSE) for NMSCs in H-zone lesions of the face. There is paucity of data regarding the 2 treatments in other areas such as the non-H-zone areas of the face, the trunk, and extremities. Our study focused on the efficacy of the 2 treatments in areas of the body where the skin was not of premium. METHOD: A retrospective chart review was performed of patients with NMSCs treated with TSE at the West Los Angeles Veterans Affairs Hospital between 2000 and 2008. Patients with at least a 3-year follow-up were selected for the study. Institutional review board approval was obtained before commencement of the study. Age, sex, and race-matched patients were selected in the MMS group. Data collected included demographic data, tumor characteristics, surgical treatment, reconstructions, recurrence rates, complications, and follow-up course. Data were analyzed using SigmaStat 3.5. RESULTS: A total of 588 patients were treated for NMSCs at our institute between 2000 and 2008, of which 289 patients had non-H-zone, extremity, and trunk lesions. The follow-up period for these patients was at least 3 years. Average age of this group was 67.1 (11.4) with 89.9% being males. Age, sex, and race-matched group of 200 patients treated with MMS for NMSCs were randomly chosen from the same time range. Average size of lesions was 17.4 (16.9) mm in the TSE group and 1.1 (0.4) mm in the MMS group (P < 0.05). Primary reconstruction was performed in non-premium areas (ie, non-H-zone areas of the face, the trunk, and extremities) in 98.7% patients in the TSE group and 61.5% patients in the MMS group (P < 0.05). Secondary reconstructive rate was 1.3% in TSE compared to 37.5% in MMS. Overall recurrence rate was 4.8% (compared to 3% with MMS). Of the 29 patients who had recurrences within the TSE group, 27 were H-zone lesions and 2 were non-H-zone lesions. DISCUSSION: One of the primary goals of NMSC management is to treat the lesion with adequate oncologic margins, while preserving maximal function and cosmesis. Our data look at the non-premium areas to quantify the clinical efficacy of TSE versus MMS. The size of lesions treated by TSE was significantly larger than those treated by MMS in all areas of the body. The primary closure rates were significantly higher and secondary procedure rates significantly lower in the TSE group compared to the MMS group, in non-premium areas. Our data suggest that patients with NMSCs may be more effectively treated with TSE than MMS in non-premium areas of the body. Additional studies are ongoing, including economic modeling and cost analysis.

Gender Affirming Surgery in Nonbinary Patients: A Single Institutional Experience.

Background An increasing number of nonbinary patients are receiving gender-affirming procedures due to improved access to care. However, the preferred treatments for nonbinary patients are underdescribed. The purpose of this study was to investigate the goals and treatments of nonbinary patients. Methods A retrospective study of patients who self-identified as nonbinary from our institutional Gender Health Program was conducted. Patient demographics, clinical characteristics, surgical goals, and operative variables were analyzed. Results Of the 375 patients with gender dysphoria, 67 (18%) were nonbinary. Over half of the nonbinary patients were assigned male at birth ( n = 57, 85%) and nearly half preferred the gender pronoun they/them/theirs ( n = 33, 49%). A total of 44 patients (66%) received hormone therapy for an average of 2.5 ± 3.6 years, primarily estrogen ( n = 39). Most patients ( n = 46, 69%) received or are interested in gender-affirming surgery, of which, almost half were previously on hormone therapy ( n = 32, 48%). The most common surgeries completed or desired were facial feminization surgery ( n = 15, 22%), vaginoplasty ( n = 15, 22%), mastectomy ( n = 11, 16%), and orchiectomy ( n = 9, 13%). Nonbinary patients who were assigned male at birth (NB-AMAB) were more often treated with hormones compared to nonbinary patients assigned female at birth (NB-AFAB) (72% vs. 30%, p = 0.010). Conversely, patients who were AFAB were more likely to complete or desire surgical intervention than those who were AMAB (100% vs. 63.0%, p < 0.021). Conclusion Majority of nonbinary patients were assigned male at birth. NB-AFAB patients all underwent surgical treatment, whereas NB-AMAB patients were predominantly treated with hormone therapy.

Systematic Review of the Impact of Acellular Dermal Matrix on Aesthetics and Patient Satisfaction in Tissue Expander-to-Implant Breast Reconstructions.

BACKGROUND: Acellular dermal matrix is used in most postmastectomy implant-based breast reconstructions in the United States. It is believed to be safe, despite a slightly increased complication rate. Although never established in a unifying study, the primary advantage of acellular dermal matrix is believed to be an enhanced aesthetic result, thus justifying the added expense. The purpose of this study was to assess the aesthetic benefits of acellular dermal matrix in expander-to-implant breast reconstruction. METHODS: A systematic review adhering to Preferred Reporting Items for Systematic Reviews and Meta-Analyses methodology was performed including all original studies examining aesthetic outcomes of expander-to-implant breast reconstructions with acellular dermal matrix compared to muscular coverage. Direct-to-implant and prepectoral studies were excluded from the evaluation. The results were aggregated and reported as a summary. RESULTS: Among 883 studies identified, 49 full-text articles were reviewed and nine articles ultimately met inclusion criteria. All nine studies were not randomized. Of these, three articles (1448 total patients) evaluated reconstruction aesthetic outcomes by patient satisfaction, whereas six articles evaluated the aesthetic outcomes by external observer (504 total patients). None of the articles evaluating patient satisfaction reported a difference between acellular dermal matrix and muscular reconstruction. Five of the six articles using objective outcomes demonstrated significant improvement in aesthetic outcome in the acellular dermal matrix group. CONCLUSIONS: Although little evidence exists evaluating the aesthetic benefits of acellular dermal matrix for expander-to-implant breast reconstruction, the data suggest that objective observers consider acellular dermal matrix-assisted expander-to-implant breast reconstructions aesthetically superior to reconstruction with only muscular coverage, but patients appear to be equally satisfied with both reconstructive options.

CASE REPORT Treatment of a Lower Extremity Lymphocele With Intraoperative Lymphatic Mapping.

OBJECTIVE: Lower extremity lymphoceles secondary to saphenous vein grafting are exceptionally rare and there is only 1 previously reported case in the English literature. Data on treatment of lower extremity lymphoceles are limited and based on studies of groin lymphoceles. We discuss operative resection with selective ligation of feeding lymphatic vessels as a treatment option of lower extremity lymphoceles. METHODS: A 64-year-old man who had undergone coronary artery bypass grafting 6 years prior presented with a left lower extremity mass at the site where his saphenous vein had been harvested. Examination demonstrated a 12-cm, mobile, nonpulsatile mass at his medial left calf. The findings of magnetic resonance imaging were consistent with a lymphocele. RESULTS: Intraoperative injection of isosulfan blue dye was used to identify feeding lymphatic vessels and the lymphocele cavity was excised. Leg drains were discontinued after 3 days, and the patient was discharged home after 6 days. CONCLUSION: Operative resection with isosulfan blue dye lymphatic mapping and selective ligation of lymphatic vessels is a viable treatment of lower extremity lymphoceles.

In vitro mineralization of human mesenchymal stem cells on three-dimensional type I collagen versus PLGA scaffolds: a comparative analysis.

BACKGROUND: Development of a tissue engineered bone graft requires efficient bioactivity screening of biomaterials in clinically relevant three-dimensional systems. The authors analyzed the relative osteogenic potential of two three-dimensional biomaterials--type I collagen and poly(L-lactide-co-glycolide) (PLGA)--to support in vitro mineralization of human mesenchymal stem cells. METHODS: Human mesenchymal stem cells were seeded onto three-dimensional PLGA or type I collagen scaffolds; incubated in osteogenic media; and harvested at 1, 4, and 7 days. Messenger RNA expression was analyzed using quantitative real-time reverse-transcriptase polymerase chain reaction for osteogenic (i.e., alkaline phosphatase, osteocalcin, bone sialoprotein, Runx2/core binding factor α-1) and angiogenic (i.e., vascular endothelial growth factor and interleukin-8) markers. Alkaline phosphatase enzyme activity was measured at 4 and 7 days. Mineralization was detected by alizarin red staining and micro-computed tomographic imaging at 8 and 12 weeks. Mineral composition was analyzed by solid-phase nuclear magnetic resonance spectroscopy. RESULTS: Early osteogenic and angiogenic markers, and alkaline phosphatase enzyme activity, were up-regulated on PLGA versus collagen scaffolds. However, long-term mineralization endpoints favored type I collagen. By 8 weeks, human mesenchymal stem cells on collagen exhibited significantly higher mineral density by micro-computed tomographic and alizarin red staining than PLGA scaffolds. Both biomaterials deposited calcium hydroxyapatite as determined by nuclear magnetic resonance spectroscopy. CONCLUSIONS: The authors' findings suggest that despite early PLGA induction of osteogenic gene expression, long-term mineralization occurs earlier and to a greater extent on type I collagen, highlighting collagen as a potential bone tissue engineering scaffold in the human mesenchymal stem cell niche. When screening the relative osteoinductive profiles of three-dimensional bone tissue engineering scaffolds in vitro, the authors recommend including long-term endpoints of osteogenesis.

Extracellular-signal-related kinase 1/2 is responsible for inhibition of osteogenesis in three-dimensional cultured MC3T3-E1 cells.

We have previously demonstrated that osteogenic differentiation is inhibited and angiogenic expression is enhanced in murine preosteoblasts (MC3T3-E1) cultured on three-dimensional (3D) poly-L-lactide-co-glycolide (PLGA) scaffolds when compared to two-dimensional (2D) PLGA films. In the present work we investigated the role of the extracellular signal-related kinase 1/2 (ERK1/2) pathway in modulating osteogenic and angiogenic differentiation in 2D and 3D systems made of two distinct biomaterials-type I collagen and PLGA. The addition of a third dimension, regardless of biomaterials, substantially increased ERK1/2 activation as demonstrated by an increase in phosphorylated ERK1/2. Western blot analysis showed significant increases in phosphorylation of ERK1/2 in cells grown in 3D versus 2D cultures at day 4 (5- and 7.7-fold increases 3D vs. 2D in collagens and PLGA, respectively) and day 7 (4.7- and 4.6-fold increases 3D vs. 2D in collagen and PLGA, respectively). Using an ERK-specific inhibitor, PD 98059, we established a correlation between ERK activation and inhibited osteogenic differentiation. Inhibition of ERK activation in 3D cultures significantly enhanced osteogenic differentiation. It in fact restored osteogenic differentiation to a level equal to that of 2D cultured cells. Inhibition of ERK1/2, however, showed little effect on angiogenic gene expression, indicating that two distinct mechanisms are involved in osteogenic and angiogenic differentiation. Taken together, these results allow us to report a mechanistic model in MC3T3-E1 cells in which distinct activation of ERK1/2 in 3D culture has an inhibitory effect on osteogenic differentiation.

Magnetic resonance imaging characterization of orbital changes with age and associated contributions to lower eyelid prominence.

BACKGROUND: Multiple orbital aging models have been suggested to explain the progressive development of lower eyelid prominence. Objective data to support these theories are limited, however. METHODS: Orbital anatomy was measured with high-resolution orbital magnetic resonance imaging in the quasi-sagittal plane parallel to the long axis of the orbit passing through the globe center. The association between measurements and age was analyzed by stratifying subjects into predetermined age groups and as a continuous variable. RESULTS: Forty subjects (17 men and 23 women) were imaged and are reported by age group: 12 to 29 years, 30 to 54 years, and 55 to 80 years. Inferior periocular soft-tissue area anterior to the anteroposterior globe axis increased with age: 99, 103, and 131 mm (p = 0.008), respectively. The largest contributor to this size increase was fat expansion: 28, 31, and 43 mm (p = 0.009), respectively. Total orbital fat also increased with age: 335, 377, and 398 mm, respectively (p = 0.035). The globe position relative to the inferior orbit in both the anteroposterior and the superoinferior planes remained unchanged. CONCLUSIONS: The authors' measurements suggest that with aging there is a significant increase in anterior inferior periocular soft-tissue volume, and that fat expansion is the main contributor to this volume increase. These observations provide supporting evidence that orbital fat expansion occurs with age and is the primary age-associated contributor to lower eyelid prominence, rather than globe descent or fat repositioning caused by weakening of the orbital septum. We believe these data suggest that fat excision should be a component of treatment for lower eyelid prominence.

Genetic markers of osteogenesis and angiogenesis are altered in processed lipoaspirate cells when cultured on three-dimensional scaffolds.

BACKGROUND: Liposuction-derived stem cells (processed lipoaspirate) have recently been shown to be capable of differentiating into bone. Most studies on osteoblastic growth and differentiation have been conducted in a conventional two-dimensional culture system; however, in native bone, osteoblasts are situated in a three-dimensional configuration. There have been limited studies of processed lipoaspirate behavior in three-dimensional systems. The authors studied the influence a three-dimensional scaffold has on the expression of genes related to osteogenesis and angiogenesis in processed lipoaspirate cells. METHODS: One million processed lipoaspirate cells were seeded onto two-dimensional poly(l-lactide-co-glycolide) films or in three-dimensional poly(l-lactide-co-glycolide) scaffolds and incubated in osteogenic medium up to 21 days. RNA was extracted and analyzed with quantitative real-time polymerase chain reaction. RESULTS: When an inert three-dimensional poly(l-lactide-co-glycolide) scaffold was introduced, the pattern and sequence of gene expression changed significantly. Processed lipoaspirate cells cultured onto three-dimensional scaffolds had increased expression of interleukin-8 and vascular endothelial growth factor compared with two-dimensional controls at early time points. Osteogenesis markers-alkaline phosphatase, collagen type I, osteocalcin, osteonectin, and osteopontin-were significantly up-regulated in three-dimensional cultures relative to two-dimensional controls after 24 hours and persisted throughout the 21 days. CONCLUSIONS: In human processed lipoaspirate cells, the introduction of a three-dimensional scaffold significantly enhances gene markers of angiogenesis and osteogenesis. On three-dimensional scaffolds, processed lipoaspirate cells first up-regulate genes involved with vascular ingrowth and then those involved in bone formation. We believe these differences will significantly impact the design of a bone graft substitute for clinical application.

Pretreatment of poly(l-lactide-co-glycolide) scaffolds with sodium hydroxide enhances osteoblastic differentiation and slows proliferation of mouse preosteoblast cells.

BACKGROUND: Surface topography is important in the creation of a scaffold for tissue engineering. Chemical etching of poly(l-lactide-co-glycolide) with sodium hydroxide has been shown to enhance adhesion and function of numerous cell types. The authors investigated the effects of sodium hydroxide pretreatment of three-dimensional poly(l-lactide-co-glycolide) scaffolds on the adhesion, differentiation, and proliferation of MC3T3-E1 murine preosteoblasts. METHODS: MC3T3-E1 cells were seeded onto three-dimensional poly(l-lactide-co-glycolide) scaffolds with and without 1 M sodium hydroxide pretreatment. Cells were then cultured in osteogenic medium and harvested at varying time points for RNA extraction. Quantitative real-time reverse-transcriptase polymerase chain reaction was performed to measure mRNA expression of several osteogenic marker genes. In addition, cell numbers were determined at varying time points during the culture period. All experiments were performed in triplicate. RESULTS: Pretreatment of three-dimensional poly(l-lactide-co-glycolide) scaffolds with sodium hydroxide resulted in statistically significant up-regulation of mRNA expression of alkaline phosphatase, bone sialoprotein, osteocalcin, and vascular endothelial growth factor during the first 10 days of culture. Histologic analysis demonstrated a striking increase in mineralized cell matrix deposition in the sodium hydroxide-treated group. Cell number was statistically higher in the sodium hydroxide-treated group immediately after cell seeding, suggesting improved adhesion. During the first 24 hours of culture, cells grew faster in the control group than in the sodium hydroxide-treated group. CONCLUSIONS: Chemical etching of poly(l-lactide-co-glycolide) scaffolds with sodium hydroxide strongly influences the behavior of MC3T3-E1 preosteoblasts in vitro by enhancing adhesion and differentiation and slowing proliferation. Sodium hydroxide treatment may represent a simple and inexpensive way of improving scaffolds for use in bone tissue engineering.

Incidence and management of abdominal wall defects after intestinal and multivisceral transplantation.

BACKGROUND: Successful primary closure of the abdominal wall following visceral organ transplantation is not always feasible. Primary closure under tension can lead to fascial ischemia or necrosis, with subsequent dehiscence. Thus, alternate techniques to achieve abdominal wall closure are an important technical aspect in intestinal transplantation. The authors review their experience managing abdominal wall defects following intestinal or multivisceral transplantation. METHODS: A retrospective review of the transplant database revealed 28 intestinal transplants in 24 patients from program inception in 1991 to January of 2002. The management of six intestinal transplant recipients with giant posttransplant abdominal wall defects is reviewed, and a novel technique is described for initially managing defects with prosthetic grafts that were serially reduced in size until a clean granulating bed was established, at which time they underwent permanent coverage using a meshed split-thickness skin graft. RESULTS: Of the 28 transplants, primary fascial closure was possible in only 14. In the other 14 patients, the fascia could not be closed primarily at the time of transplantation. The donor weight-to-recipient weight ratio was significantly greater in patients with abdominal wall closure problems (0.64 versus 1.09; p < 0.005). The incidence of retransplantation was also higher in those with abdominal closure problems compared with those whose fascia could be closed primarily (five of 14 versus one of 14). The six patients managed with skin graft closure did not have any wound complications after grafting. CONCLUSIONS: Abdominal wall defect after intestinal and multivisceral transplantation is a common problem without an ideal solution. Use of a skin graft on granulating abdominal viscera frozen with adhesions is a simple and reasonable solution to a complex problem.

Characterization of growth and osteogenic differentiation of rabbit bone marrow stromal cells.

BACKGROUND: The rabbit is recognized as an excellent model to study the repair of bony defects with tissue engineered constructs. However, the use of rabbit bone marrow stromal cells (RBMSCs) has been limited despite the proven benefits of autologous BMSCs in the formation of bone. The purpose of this study was to characterize the growth and differentiation pattern of RBMSCs and their response to growth factors. MATERIAL AND METHODS: BMSCs were isolated from New Zealand White rabbits and cultured. Serial cell counts of parallel cultures were taken daily to determine cell growth. Response of RBMSCs to varying doses of recombinant human BMP-2 (rhBMP-2) and their time course was gauged by alkaline phosphatase (ALP) activity. The osteoblastic differentiation potential of RBMSCs in response to rhBMP-2 treatment was determined by evaluating the expression pattern of various genes involved with osteogensis using northern analysis. Von Kossa staining was performed to determine the effect of rhBMP-2 on the mineralization capabilities of RBMSCs. RESULTS: The growth rate of RBMSCs severely declined after first passage and this rate was further suppressed by TGF-beta1. The optimal dose response of rhBMP-2 was determined to be 50 ng/ml and its time course displayed increasing alkaline phosphatase activity over time. Two osteogenic markers, collagen I and osteopontin, were up regulated by rhBMP-2 treatment. Finally, the mineralization capability of RBMSCs was determined to be enhanced by rhBMP-2 treatment. CONCLUSION: Our work indicates that RBMSCs possess strong osteogenic potential and can be successfully applied toward bone tissue engineering in a rabbit model.

Osteogenic differentiation is inhibited and angiogenic expression is enhanced in MC3T3-E1 cells cultured on three-dimensional scaffolds.

Osteogenic differentiation of osteoprogenitor cells in three-dimensional (3D) in vitro culture remains poorly understood. Using quantitative real-time RT-PCR techniques, we examined mRNA expression of alkaline phosphatase, osteocalcin, and vascular endothelial growth factor (VEGF) in murine preosteoblastic MC3T3-E1 cells cultured for 48 h and 14 days on conventional two-dimensional (2D) poly(l-lactide-co-glycolide) (PLGA) films and 3D PLGA scaffolds. Differences in VEGF secretion and function between 2D and 3D culture systems were examined using Western blots and an in vitro Matrigel-based angiogenesis assay. Expression of both alkaline phosphatase and osteocalcin in cells cultured on 3D scaffolds was significantly downregulated relative to 2D controls in 48 h and 14 day cultures. In contrast, elevated levels of VEGF expression in 3D culture were noted at every time point in short- and long-term culture. VEGF protein secretion in 3D cultures was triple the amount of secretion observed in 2D controls. Conditioned medium from 3D cultures induced an enhanced level of angiogenic activity, as evidenced by increases in branch points observed in in vitro angiogenesis assays. These results collectively indicate that MC3T3-E1 cells commit to osteogenic differentiation at a slower rate when cultured on 3D PLGA scaffolds and that VEGF is preferentially expressed by these cells when they are cultured in three dimensions.

Overexpression of BMP-2 modulates morphology, growth, and gene expression in osteoblastic cells.

Bone morphogenetic proteins (BMP) play a pivotal role in growth and differentiation of osteoblastic lineage cells. BMPs are potent stimulators of bone formation in various animal models. To understand the mechanism of BMP action in bone cells, we have investigated the effects of overexpression of the BMP-2 gene on proliferation and differentiation of UMR-106 rat osteosarcoma cells. A stable UMR-106 cell line overexpressing the BMP-2 gene was established by transfection of cells using a mammalian expression vector harboring human BMP-2 cDNA followed by G418 selection. After introduction of the BMP-2 gene, UMR-106 cells appeared more spindle-shaped in morphology compared to the predominantly cuboidal appearance of the parental cells. Overexpression of BMP-2 markedly inhibited proliferation as measured by cell counting and [3H]thymidine incorporation assays. Extracellular matrix (ECM) derived from cells overexpressing BMP-2 exhibited a less supportive effect on proliferation of UMR cells than did ECM derived from parental cells. Furthermore, cell-cell communication through gap junctions was reduced more than 50% as determined by nondisruptive fluorescent dye transfer assays. Overexpression of BMP-2 significantly stimulated expression of osteocalcin and alkaline phosphatase genes, indicating its role in osteoblastic differentiation. There was little effect on osteopontin gene expression.

Retinoids inhibit squamous cell carcinoma growth and intercellular communication.

BACKGROUND: Retinoids have been shown to inhibit the growth of squamous cell carcinoma and other malignancies. They have also been shown to alter gap junctional intercellular communication (GJIC) and the expression of connexins, the protein subunits of gap junctions. We report in this study that the alteration of GJIC by retinoids may be directly related to inhibitory effects on cell growth. MATERIALS AND METHODS: SCC-13 cells were treated with all-trans retinoic acid (tRA) and 13-cis retinoic acid (cRA) at 10(-7) and 10(-6) M concentrations in culture. No treatment and ethanol vehicle controls were included for each experiment. Serial cell counts of parallel cultures were performed to determine cell growth. The parachute technique was performed in combination with fluorescence activated cell sorting (FACS) analysis to determine GJIC. Northern and Western blot analysis were performed to assess connexin mRNA and protein expression. RESULTS: The growth rate was inhibited for cells treated with tRA (10(-6) M) (P < 0.05) and cRA (10(-6) M) (P = 0.068) vs. vehicle control. GJIC was significantly inhibited with both tRA (10(-7) and 10(-6) M) (P < 0.001) and cRA (10(-7) and 10(-6) M) (P < 0.001) at 24, 48, and 96 h as determined by FACS analysis. To correlate GJIC with cell growth, we studied the effect of glycyrrhetinic acid, a known inhibitor of GJIC. Glycyrrhetinic acid also significantly inhibited cell growth (P < 0.05) vs. control. Connexin 26 and connexin 43 mRNA and protein expression were not significantly altered after retinoid treatment. CONCLUSION: Retinoic acids inhibit both cell growth and GJIC in SCC-13 cells. Retinoids may inhibit cell growth through alteration of GJIC in SCC-13 cells.