Joseph P Vacanti

Publications of Joseph P Vacanti

• Three-Dimensionally Printed Polycaprolactone and β-Tricalcium Phosphate Scaffolds for Bone Tissue Engineering: An In Vitro Study.

  Authors: Basel Sharaf, Caroline B Faris, Harutsugi Abukawa, Srinivas M Susarla, Joseph P Vacanti, Leonard B Kaban, Maria J Troulis

  Journal of oral and maxillofacial surgery : official journal of the American Association of Oral and Maxillofacial Surgeons. 11/2011; 70(3):647-56.

  The purpose of this study was to evaluate porcine bone marrow-derived progenitor cell (pBMPC) proliferation and penetration into a novel 3-dimensionally printed scaffold. Four different tissueThe purpose of this study was to evaluate porcine bone marrow-derived progenitor cell (pBMPC) proliferation and penetration into a novel 3-dimensionally printed scaffold. Four different tissue engineering scaffolds to evaluate pBMPC proliferation and penetration were examined. Scaffolds were fabricated from polycaprolactone (PCL) or the combination of β-tricalcium phosphate (β-TCP) and PCL (50:50), with 2 separate channel sizes (1 mm [small (S)] vs 2 mm [large (L)]). Scaffolds were fabricated into 20 × 20 × 7-mm blocks by use of a TheriForm machine (Integra Life Sciences, Akron, OH). Four groups of scaffolds were examined for pBMPC proliferation and penetration: group 1, β-TCP/PCL S; group 2, β-TCP/PCL L; group 3, PCL S; and group 4, PCL L. Nonparametric mean (Kruskal-Wallis) and multiple comparisons tests were used to compare the 4 groups. No shrinkage or deformation was noted in any of the scaffold groups after 2 weeks of culture. Mean surface cell counts ranged from 13.4 to 87.8 cells/0.57 mm(2), with group 1 (β-TCP/PCL S) having statistically significantly higher counts than the other groups (P < .001). Mean interior cell counts ranged from 10.9 to 75.6 cells/0.57 mm(2), with group 1 having the greatest interior cell count (P < .001). Total collagen formation ranged from 0.2% to 86%, with group 1 having the highest collagen formation (P < .001). The 3-dimensionally printed scaffold (β-TCP/PCL) with 1-mm channels showed greater cellular proliferation, penetration, and collagen formation after a 2-week in vitro culture than the other scaffolds evaluated. β-TCP/PCL S scaffolds warrant further evaluation for bone tissue engineering in vivo.

• Enhanced in vivo function of bioartificial lungs in rats.

  Authors: Jeremy J Song, Sam S Kim, Zhilin Liu, Joren C Madsen, Douglas J Mathisen, Joseph P Vacanti, Harald C Ott

  The Annals of thoracic surgery. 09/2011; 92(3):998-1005; discussion 1005-6.

  More than 11 million Americans live with chronic lung disease; in search for an alternative to donor organs, we attempted to regenerate lungs based on perfusion decellularized lung scaffolds that canMore than 11 million Americans live with chronic lung disease; in search for an alternative to donor organs, we attempted to regenerate lungs based on perfusion decellularized lung scaffolds that can be transplanted similar to a donor organ. Cadaveric rat lungs were decellularized by detergent perfusion. Resulting scaffolds were mounted in bioreactors and seeded with endothelial and fetal lung cells. Biomimetic organ culture was maintained for 7 days. Resulting bioartificial left lungs were transplanted in orthotopic position after left pneumonectomy in rats. Cadaveric left lung transplants and pneumonectomies served as controls. Blood gas analyses, compliance testing, and fluoroscopies were performed on postoperative days 1, 7, and 14. Lungs were removed for final analysis on day 14. Perfusion decellularization of cadaveric lungs yielded acellular scaffolds with intact architecture and matrix composition. Alveolar volumes, number, and size were comparable in bioartificial and native lungs, as were gas exchange, vital capacity and compliance in vitro. After using improved graft preservation and postoperative weaning protocols, animals could be fully recovered, and bioartificial lung constructs provided oxygenation as long as 7 days at levels comparable to cadaveric lung transplants. Compliance, gas exchange, and radiographic appearance gradually declined over the subsequent 7 days owing to progressive graft consolidation and inflammation. Perfusion decellularization of cadaveric lungs yields intact scaffolds that can be seeded with cells to generate bioartificial lung grafts. After orthotopic transplantation, grafts are perfused by the recipient's circulation, ventilated through the recipient's airway and provide gas exchange in vivo for 7 days.

• Ultra-thin, gas permeable free-standing and composite membranes for microfluidic lung assist devices.

  Authors: Ramaswamy Sreenivasan, Erik K Bassett, David M Hoganson, Joseph P Vacanti, Karen K Gleason

  Biomaterials. 03/2011; 32(16):3883-9.

  Membranes for a lung assist device must permit the exchange of gaseous O₂ and CO₂ while simultaneously acting as a liquid barrier, so as to prevent leakage of blood and its components from passingMembranes for a lung assist device must permit the exchange of gaseous O₂ and CO₂ while simultaneously acting as a liquid barrier, so as to prevent leakage of blood and its components from passing from one side to the other. Additionally, these membranes must be capable of being integrated into microfluidic devices possessing a vascular network. In this work, uniform, large-area, ultra-thin, polymeric free-standing membranes (FSMs) and composite membranes (CMs) are reproducibly fabricated by initiated Chemical Vapor Deposition (iCVD). The 5 μm thick FSMs remained intact during handling and exhibited a CO₂ permeance that was 1.3 times that of the control membrane (8 μm thick spun-cast membrane of silicone). The CMs consisted of a dense iCVD skin layer (0.5-3 μm thick) deposited on top of a polytetrafluoroethylene (PTFE) support membrane (20 μm thick, 100 nm pores). The CMs exhibited CO₂ and O₂ permeance values 50-300 times that of the control membrane. The FSMs were subjected to mechanical testing to assess the impact of the absence of an underlying support structure. The CMs were subjected to liquid barrier tests to ensure that while they were permeable to gases, they acted as barriers to liquids. Both FSMs and CMs were integrated into silicone microfluidic devices and tested for bond integrity.

• Lung assist device technology with physiologic blood flow developed on a tissue engineered scaffold platform.

  Authors: David M Hoganson, Howard I Pryor, Erik K Bassett, Ira D Spool, Joseph P Vacanti

  Lab on a chip. 02/2011; 11(4):700-7.

  There is no technology available to support failing lung function for patients outside the hospital. An implantable lung assist device would augment lung function as a bridge to transplant orThere is no technology available to support failing lung function for patients outside the hospital. An implantable lung assist device would augment lung function as a bridge to transplant or possible destination therapy. Utilizing biomimetic design principles, a microfluidic vascular network was developed for blood inflow from the pulmonary artery and blood return to the left atrium. Computational fluid dynamics analysis was used to optimize blood flow within the vascular network. A micro milled variable depth mold with 3D features was created to achieve both physiologic blood flow and shear stress. Gas exchange occurs across a thin silicone membrane between the vascular network and adjacent alveolar chamber with flowing oxygen. The device had a surface area of 23.1 cm(2) and respiratory membrane thickness of 8.7 ± 1.2 μm. Carbon dioxide transfer within the device was 156 ml min(-1) m(-2) and the oxygen transfer was 34 ml min(-1) m(-2). A lung assist device based on tissue engineering architecture achieves gas exchange comparable to hollow fiber oxygenators yet does so while maintaining physiologic blood flow. This device may be scaled up to create an implantable ambulatory lung assist device.

• Branched vascular network architecture: a new approach to lung assist device technology.

  Authors: David M Hoganson, Jennifer L Anderson, Eli F Weinberg, Eric J Swart, Brian K Orrick, Jeffrey T Borenstein, Joseph P Vacanti

  The Journal of thoracic and cardiovascular surgery. 11/2010; 140(5):990-5.

  A lung assist device would serve an important clinical need as a bridge to transplant or destination therapy for patients with end-stage lung disease. A new lung assist device has been developed thatA lung assist device would serve an important clinical need as a bridge to transplant or destination therapy for patients with end-stage lung disease. A new lung assist device has been developed that incorporates a branched network of vascular channels adjacent to a gas chamber, separated by a thin, gas-permeable membrane. This study investigated 2 potential gas exchange membranes within this new architecture. Oxygen and carbon dioxide exchange within the device was tested in vitro using 3 gas-permeable membranes. Two of the membranes, silicone only and silicone-coated microporous polymer, were plasma impermeable. The third, a microporous polymer, was used as a control. Gas exchange testing was done using anticoagulated porcine blood over a range of flow rates. Oxygen and carbon dioxide transfer was demonstrated in the device and increased nearly linearly from 0.6 to 8.0 mL/min blood flow for all of the membranes. There was no significant difference in the gas transfer between the silicone and the silicone-coated microporous polymer membranes. The transfer of oxygen and carbon dioxide in the device was similar to existing hollow fiber oxygenators controlling for surface area. The silicone and silicone-coated microporous polymer membranes both show promise as gas-permeable membranes in a new lung assist device design. Further optimization of the device by improving the membranes and reducing the channel diameter in the vascular network will improve gas transfer. The current device may be scaled up to function as an adult lung assist device.

• The retention of extracellular matrix proteins and angiogenic and mitogenic cytokines in a decellularized porcine dermis.

  Authors: David M Hoganson, Elisabeth M O'Doherty, Gwen E Owens, Dina O Harilal, Scott M Goldman, Chris M Bowley, Craig M Neville, Russell T Kronengold, Joseph P Vacanti

  Biomaterials. 09/2010; 31(26):6730-7.

  Decellularized dermis materials demonstrate considerable utility in surgical procedures including hernia repair and breast reconstruction. A new decellularized porcine dermis material has beenDecellularized dermis materials demonstrate considerable utility in surgical procedures including hernia repair and breast reconstruction. A new decellularized porcine dermis material has been developed that retains many native extracellular matrix (ECM) proteins and cytokines. This material has substantial mechanical strength with maximum tensile strength of 141.7 +/- 85.4 (N/cm) and suture pull through strength of 47.0 +/- 14.0 (N). After processing, many ECM proteins remained in the material including collagen III, collagen IV, collagen VII, laminin and fibronectin. Glycosaminoglycans, including hyaluronic acid, were also preserved. Among several cytokines whose levels were quantified, more vascular endothelial growth factor (VEGF) and transforming growth factor beta (TGF-beta) were retained within this material than in comparable decellularized dermis materials. The retention of bioactivity was demonstrated in a cell culture assay. Because this decellularized porcine dermis material both retains significant strength and has substantial biological activity, it may promote rapid integration and repair in clinical applications.

• Preserved extracellular matrix components and retained biological activity in decellularized porcine mesothelium.

  Authors: David M Hoganson, Gwen E Owens, Elisabeth M O'Doherty, Chris M Bowley, Scott M Goldman, Dina O Harilal, Craig M Neville, Russell T Kronengold, Joseph P Vacanti

  Biomaterials. 09/2010; 31(27):6934-40.

  Mesothelium tissues such as peritoneum and pleura have a thin and strong layer of extracellular matrix that supports mesothelial cells capable of rapid healing. Decellularized porcine mesothelium wasMesothelium tissues such as peritoneum and pleura have a thin and strong layer of extracellular matrix that supports mesothelial cells capable of rapid healing. Decellularized porcine mesothelium was characterized for strength, composition of the matrix and biological activity. The tensile strength of the material was 40.65 +/- 21.65 N/cm. Extracellular matrix proteins collagen IV, fibronectin, and laminin as well as glycosaminoglycans were present in the material. Cytokines inherent in the extracellular matrix were preserved. Vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF) and transforming growth factor beta (TGF-beta) were retained and the levels of VEGF and TGF-beta in the decellularized mesothelium were higher than those found in decellularized small intestinal submucosa (SIS). The decellularized mesothelium also stimulated human fibroblasts to produce more VEGF than fibroblasts grown on tissue culture plastic. Decellularized mesothelium is a sheet material with a combination of strength and biological activity that may have many potential applications in surgical repair and regenerative medicine.

• Liver-assist device with a microfluidics-based vascular bed in an animal model.

  Authors: Wen-Ming Hsu, Amedeo Carraro, Katherine M Kulig, Mark L Miller, Mohammad Kaazempur-Mofrad, Eli Weinberg, Fateh Entabi, Hassan Albadawi, Michael T Watkins, Jeffrey T Borenstein, Joseph P Vacanti, Craig Neville

  Annals of surgery. 08/2010; 252(2):351-7.

  This study evaluates a novel liver-assist device platform with a microfluidics-modeled vascular network in a femoral arteriovenous shunt in rats. Liver-assist devices in clinical trials that useThis study evaluates a novel liver-assist device platform with a microfluidics-modeled vascular network in a femoral arteriovenous shunt in rats. Liver-assist devices in clinical trials that use pumps to force separated plasma through packed beds of parenchymal cells exhibited significant necrosis with a negative impact on function. Microelectromechanical systems technology was used to design and fabricate a liver-assist device with a vascular network that supports a hepatic parenchymal compartment through a nanoporous membrane. Sixteen devices with rat primary hepatocytes and 12 with human HepG2/C3A cells were tested in athymic rats in a femoral arteriovenous shunt model. Several parenchymal tube configurations were evaluated for pressure profile and cell survival. The blood flow pattern and perfusion status of the devices was examined by laser Doppler scanning. Cell viability and serum protein secretion functions were assessed. Femoral arteriovenous shunt was successfully established in all animals. Blood flow was homogeneous through the vascular bed and replicated native flow patterns. Survival of seeded liver cells was highly dependent on parenchymal chamber pressures. The tube configuration that generated the lowest pressure supported excellent cell survival and function. This device is the first to incorporate a microfluidics network in the systemic circulatory system. The microvascular network supported viability and function of liver cells in a short-term ex vivo model. Parenchymal chamber pressure generated in an arteriovenous shunt model is a critical parameter that affects viability and must be considered in future designs. The microfluidics-based vascular network is a promising platform for generating a large-scale medical device capable of augmenting liver function in a clinical setting.

• Regeneration and orthotopic transplantation of a bioartificial lung.

  Authors: Harald C Ott, Ben Clippinger, Claudius Conrad, Christian Schuetz, Irina Pomerantseva, Laertis Ikonomou, Darrell Kotton, Joseph P Vacanti

  Nature medicine. 08/2010; 16(8):927-33.

  About 2,000 patients now await a donor lung in the United States. Worldwide, 50 million individuals are living with end-stage lung disease. Creation of a bioartificial lung requires engineering ofAbout 2,000 patients now await a donor lung in the United States. Worldwide, 50 million individuals are living with end-stage lung disease. Creation of a bioartificial lung requires engineering of viable lung architecture enabling ventilation, perfusion and gas exchange. We decellularized lungs by detergent perfusion and yielded scaffolds with acellular vasculature, airways and alveoli. To regenerate gas exchange tissue, we seeded scaffolds with epithelial and endothelial cells. To establish function, we perfused and ventilated cell-seeded constructs in a bioreactor simulating the physiologic environment of developing lung. By day 5, constructs could be perfused with blood and ventilated using physiologic pressures, and they generated gas exchange comparable to that of isolated native lungs. To show in vivo function, we transplanted regenerated lungs into orthotopic position. After transplantation, constructs were perfused by the recipient's circulation and ventilated by means of the recipient's airway and respiratory muscles, and they provided gas exchange in vivo for up to 6 h after extubation.

• Engineered vascularized bone grafts.

  Authors: Olga Tsigkou, Irina Pomerantseva, Joel A Spencer, Patricia A Redondo, Alison R Hart, Elisabeth O'Doherty, Yunfeng Lin, Claudia C Friedrich, Laurence Daheron, Charles P Lin, Cathryn A Sundback, Joseph P Vacanti, Craig Neville

  Proceedings of the National Academy of Sciences of the United States of America. 02/2010; 107(8):3311-6.

  Clinical protocols utilize bone marrow to seed synthetic and decellularized allogeneic bone grafts for enhancement of scaffold remodeling and fusion. Marrow-derived cytokines induce hostClinical protocols utilize bone marrow to seed synthetic and decellularized allogeneic bone grafts for enhancement of scaffold remodeling and fusion. Marrow-derived cytokines induce host neovascularization at the graft surface, but hypoxic conditions cause cell death at the core. Addition of cellular components that generate an extensive primitive plexus-like vascular network that would perfuse the entire scaffold upon anastomosis could potentially yield significantly higher-quality grafts. We used a mouse model to develop a two-stage protocol for generating vascularized bone grafts using mesenchymal stem cells (hMSCs) from human bone marrow and umbilical cord-derived endothelial cells. The endothelial cells formed tube-like structures and subsequently networks throughout the bone scaffold 4-7 days after implantation. hMSCs were essential for stable vasculature both in vitro and in vivo; however, contrary to expectations, vasculature derived from hMSCs briefly cultured in medium designed to maintain a proliferative, nondifferentiated state was more extensive and stable than that with hMSCs with a TGF-beta-induced smooth muscle cell phenotype. Anastomosis occurred by day 11, with most hMSCs associating closely with the network. Although initially immature and highly permeable, at 4 weeks the network was mature. Initiation of scaffold mineralization had also occurred by this period. Some human-derived vessels were still present at 5 months, but the majority of the graft vasculature had been functionally remodeled with host cells. In conclusion, clinically relevant progenitor sources for pericytes and endothelial cells can serve to generate highly functional microvascular networks for tissue engineered bone grafts.

• Mechanical dissociation of swine liver to produce organoid units for tissue engineering and in vitro disease modeling.

  Authors: Katayun Irani, Irina Pomerantseva, Alison R Hart, Cathryn A Sundback, Craig M Neville, Joseph P Vacanti

  Artificial organs. 01/2010; 34(1):75-8.

  The complex intricate architecture of the liver is crucial to hepatic function. Standard protocols used for enzymatic digestion to isolate hepatocytes destroy tissue structure and result inThe complex intricate architecture of the liver is crucial to hepatic function. Standard protocols used for enzymatic digestion to isolate hepatocytes destroy tissue structure and result in significant loss of synthetic, metabolic, and detoxification processes. We describe a process using mechanical dissociation to generate hepatic organoids with preserved intrinsic tissue architecture from swine liver. Oxygen-supplemented perfusion culture better preserved organoid viability, morphology, serum protein synthesis, and urea production, compared with standard and oxygen-supplemented static culture. Hepatic organoids offer an alternative source for hepatic assist devices, engineered liver, disease modeling, and xenobiotic testing.

• Bone marrow derived pluripotent cells are pericytes which contribute to vascularization.

  Authors: Xiaoxiao Cai, Yunfeng Lin, Claudia C Friedrich, Craig Neville, Irina Pomerantseva, Cathryn A Sundback, Parul Sharma, Zhiyuan Zhang, Joseph P Vacanti, Peter V Hauschka, Brian E Grottkau

  Stem cell reviews. 12/2009; 5(4):437-45.

  Pericytes are essential to vascularization, but the purification and characterization of pericytes remain unclear. Smooth muscle actin alpha (alpha-SMA) is one marker [corrected] of pericytes. ThePericytes are essential to vascularization, but the purification and characterization of pericytes remain unclear. Smooth muscle actin alpha (alpha-SMA) is one marker [corrected] of pericytes. The aim of this study is to purify the alpha-SMA positive cells from bone marrow and study the characteristics of these cells and the interaction between alpha-SMA positive cells and endothelial cells. The bone marrow stromal cells were harvested from alpha-SMA-GFP transgenic mice, and the alpha-SMA-GFP positive cells were sorted by FACS. The proliferative characteristics and multilineage differentiation ability of the alpha-SMA-GFP positive cells were tested. A 3-D culture model was then applied to test their vascularization by loading alpha-SMA-GFP positive cells and endothelial cells on collagen-fibronectin gel. Results demonstrated that bone marrow stromal cells are mostly alpha-SMA-GFP positive cells which are pluripotent, and these cells expressed alpha-SMA during differentiation. The alpha-SMA-GFP positive cells could stimulate the endothelial cells to form tube-like structures and subsequently robust vascular networks in 3-D culture. In conclusion, the bone marrow derived pluripotent cells include [corrected] pericytes and can contribute to vascularization.

• Effect of ibuprofen on osteoblast differentiation of porcine bone marrow-derived progenitor cells.

  Authors: Harutsugi Abukawa, Maynard Phelps, Pamela Jackson, R Malcolm Smith, Joseph P Vacanti, Leonard B Kaban, Maria J Troulis

  Journal of oral and maxillofacial surgery : official journal of the American Association of Oral and Maxillofacial Surgeons. 11/2009; 67(11):2412-7.

  PURPOSE: Nonsteroidal anti-inflammatory drugs are commonly prescribed to reduce inflammation and pain. However, little is known about the direct effect of these drugs on the differentiation of bonePURPOSE: Nonsteroidal anti-inflammatory drugs are commonly prescribed to reduce inflammation and pain. However, little is known about the direct effect of these drugs on the differentiation of bone marrow-derived progenitor cells into osteoblasts. The purpose of this study was to determine the effect of ibuprofen on osteoblast differentiation and proliferation in a minipig model. MATERIALS AND METHODS: Bone marrow was aspirated from the minipig ilium, and porcine bone marrow-derived progenitor cells (pBMPCs) were isolated and expanded in standard culture medium. The pBMPCs were replated and differentiated into osteoblasts by use of osteogenic supplements (OS). Five groups were studied: negative control--pBMPCs in standard medium only; positive control--pBMPCs, standard culture medium, and OS; and 3 experimental groups--pBMPCs, standard culture medium, OS, and ibuprofen added in doses of 0.1, 1.0, and 3.0 mmol/L. Cell cultures were evaluated quantitatively by alkaline phosphatase (ALP) stain, von Kossa stain, and deoxyribonucleic acid (DNA) content. RESULTS: pBMPCs cultured with OS and low-dose ibuprofen (0.1 mmol/L) showed ALP stain, von Kossa stain, and DNA content similar to pBMPCs cultured in OS (positive control). pBMPCs cultured in higher doses of ibuprofen (1.0 and 3.0 mmol/L) produced significantly less positive staining of ALP and von Kossa and decreased DNA content. CONCLUSION: The results indicate that high-dose ibuprofen has a deleterious effect on pBMPC differentiation into osteoblasts whereas low-dose ibuprofen does not. The low dose of 0.1 mmol/L is the typical serum level when prescribed for clinical use.

• Pulmonary tissue engineering using dual-compartment polymer scaffolds with integrated vascular tree.

  Authors: Clemens S Fritsche, Oliver Simsch, Ely J Weinberg, Brian Orrick, Christof Stamm, Mohammad R Kaazempur-Mofrad, Jeffrey T Borenstein, Roland Hetzer, Joseph P Vacanti

  The International journal of artificial organs. 10/2009; 32(10):701-10.

  Objectives: The persistent shortage of donor organs for lung transplantation illustrates the need for new strategies in organ replacement therapy. Pulmonary tissue engineering aims at developingObjectives: The persistent shortage of donor organs for lung transplantation illustrates the need for new strategies in organ replacement therapy. Pulmonary tissue engineering aims at developing viable hybrid tissue for patients with chronic respiratory failure. Methods: Dual-chamber polymer constructs that mimic the characteristics of the pulmonary air-blood interface were fabricated by microfabrication techniques using the biocompatible polymer polydimethylsiloxane. One compartment ("vascular chamber") was designed as a capillary network to mimic the pulmonary microvasculature. The other compartment ("parenchymal chamber") was designed to permit gas exchange. Immortalized mouse lung epithelium cells (MLE-12) were cultured on the surface of polystyrene microcarrier beads. These beads were subsequently injected into the parenchymal chamber of the dual-chamber microsystems. The vascular compartment was perfused with cell culture medium in a bioreactor and the construct was maintained in culture for 1 week. Results: The microcarriers evenly distributed MLE-12 cells on the parenchymal compartment surface. Confluent cell layers were confirmed by fluorescent and electron microscopy. Adequate proliferation of MLE-12 cells within the construct was monitored via the DNA content. Viability of the cells was maintained over 1 week. Finally, cellular specificity and functional capacity in situ were demonstrated by immunostaining for proSP-B and proSP-C (alveolar epithelium), and by using MLE-12 cells transfected to overexpress green fluorescent protein. Conclusion: We conclude that functional hybrid microsystems mimicking the basic building plan of alveolar tissue can be engineered in vitro.

• Poly(glycerol sebacate) films prevent postoperative adhesions and allow laparoscopic placement.

  Authors: Howard I Pryor, Elisabeth O'Doherty, Alison Hart, Gwen Owens, David Hoganson, Joseph P Vacanti, Peter T Masiakos, Cathryn A Sundback

  Surgery. 10/2009; 146(3):490-7.

  BACKGROUND: The objectives of this study were to evaluate the efficacy of poly(glycerol) sebacate (PGS) films for the prevention of visceroparietal peritoneal (VP) adhesions and demonstrate the easeBACKGROUND: The objectives of this study were to evaluate the efficacy of poly(glycerol) sebacate (PGS) films for the prevention of visceroparietal peritoneal (VP) adhesions and demonstrate the ease of laparoscopic PGS film placement. Peritoneal adhesions occur in nearly 95% of all abdominal operations. VP adhesions can cause serious postoperative complications. The interposition of a barrier between damaged peritoneal areas during re-epithelialization has been shown to prevent adhesion formation. Current barrier products have serious drawbacks, including poor degradability, variable efficacy, and difficult handling characteristics. METHODS: The efficacy of PGS films to prevent VP adhesions was evaluated in a rat peritoneal adhesion model. The animals were evaluated for the presence of VP adhesions at 3, 5, and 8 weeks. The laparoscopic applicability of PGS films was demonstrated by placement into a juvenile porcine abdomen using standard laparoscopic equipment and techniques. RESULTS: A statistically significant 94% reduction in VP adhesion formation rate was observed between control animals (75%) and animals with a PGS film barrier (4.8%). PGS films were easily placed in the juvenile porcine abdomen and could be readily repositioned without material loss or tissue damage. CONCLUSION: PGS films possess a unique combination of properties, including biocompatibility, resorbability, and ease of handling. PGS barrier films were shown to be efficacious in reducing VP adhesions in the rat model. They also can be placed using standard laparoscopic techniques. These promising results suggest that PGS films will be effective barriers to adhesion formation for patients undergoing open and laparoscopic abdominal operations.

• Progress in tissue engineering.

  Authors: Ali Khademhosseini, Joseph P Vacanti, Robert Langer

  Scientific American. 06/2009; 300(5):64-71.

• Reconstructing mandibular defects using autologous tissue-engineered tooth and bone constructs.

  Authors: Harutsugi Abukawa, Weibo Zhang, Conan S Young, Rose Asrican, Joseph P Vacanti, Leonard B Kaban, Maria J Troulis, Pamela C Yelick

  Journal of oral and maxillofacial surgery : official journal of the American Association of Oral and Maxillofacial Surgeons. 03/2009; 67(2):335-47.

  PURPOSE: Current strategies for jaw reconstruction require multiple operations to replace bone and teeth. To improve on these methods, we investigated simultaneous mandibular and toothPURPOSE: Current strategies for jaw reconstruction require multiple operations to replace bone and teeth. To improve on these methods, we investigated simultaneous mandibular and tooth reconstruction, using a Yucatan minipig model. MATERIALS AND METHODS: Tooth and bone constructs were prepared from third molar tooth tissue and iliac-crest bone marrow-derived osteoblasts isolated from, and implanted back into, the same pig as an autologous reconstruction. Implants were harvested after 12 and 20 weeks and evaluated by x-ray, ultrahigh-resolution volume computed tomographic (VCT), histological, and immunohistochemical analyses. RESULTS: Small tooth structures were identified, and consisted of organized dentin, enamel, pulp, and periodontal ligament tissues, surrounded by new bone. No dental tissues formed in implants without tooth-bud cells, and bone regeneration was observed to a limited extent. Immunohistochemical analyses using tooth-specific and bone-specific antibodies confirmed the identity of regenerated tissues. CONCLUSIONS: This pilot study supports the feasibility of tissue-engineering approaches for coordinated autologous tooth and mandible reconstruction, and provides a basis for future improvement of this technique for eventual clinical use in humans.

• Tissue engineered hybrid tooth-bone constructs.

  Authors: Weibo Zhang, Harutsugi Abukawa, Maria J Troulis, Leonard B Kaban, Joseph P Vacanti, Pamela C Yelick

  Methods (San Diego, Calif.). 11/2008;

  Proper rehabilitation of craniofacial defects is challenging because of the complexity of the anatomy and the component tissue types. The ability to simultaneously coordinate the regeneration ofProper rehabilitation of craniofacial defects is challenging because of the complexity of the anatomy and the component tissue types. The ability to simultaneously coordinate the regeneration of multiple tissues would make reconstruction more efficient and might reduce morbidity and improve outcomes. The craniofacial complex is unique because of the presence of teeth, in addition to skin, bone, cartilage, muscle, vascular, and neural tissues since teeth naturally grow in coordination with the craniofacial skeleton, our group developed an autologous, tooth-bone hybrid model to facilitate repair of mandibular defects in the Yucatan minipig. The hybrid tooth-bone construct was prepared by combining tooth bud cell-seeded scaffolds with autologous iliac crest bone marrow derived stem cell-seeded scaffolds, which were transplanted back into surgically created mandibular defects in the same minipig. The constructs were harvested after 12 and 20 weeks of growth. The resulting bone/tooth constructs were evaluated by X-ray, ultra high-resolution volume computed tomography (VCT), histological, immunohistochemical analyses, and transmission electron microscopy (TEM). The observed formation of small tooth-like structures consisting of organized dentin, enamel, pulp, cementum, periodontal ligament, and surrounded by regenerated alveolar bone, suggests the feasibility for regeneration of teeth and associated alveolar bone, in a single procedure. This model provides an accessible method for future clinical applications in humans.

• Nanofabricated Collagen-Inspired Synthetic Elastomers for Primary Rat Hepatocyte Culture.

  Authors: Christopher J Bettinger, Katherine M Kulig, Joseph P Vacanti, Robert Langer, Jeffrey T Borenstein

  Tissue engineering. Part A. 11/2008;

  Synthetic substrates that mimic the properties of extracellular matrix proteins hold significant promise for use in systems designed for tissue engineering applications. In this report, we designed aSynthetic substrates that mimic the properties of extracellular matrix proteins hold significant promise for use in systems designed for tissue engineering applications. In this report, we designed a synthetic polymeric substrate that is intended to mimic chemical, mechanical, and topological characteristics of collagen. We found that elastomeric poly(ester amide) substrates modified with replica-molded nanotopographic features enhanced initial attachment, spreading, and adhesion of primary rat hepatocytes. Further, hepatocytes cultured on nanotopographic substrates also demonstrated reduced albumin secretion and urea synthesis, which is indicative of strongly adherent hepatocytes. These results suggest that these engineered substrates can function as synthetic collagen analogs for in vitro cell culture.

• The effect of sustained delivery of vascular endothelial growth factor on angiogenesis in tissue-engineered intestine.

  Authors: Flavio G Rocha, Cathryn A Sundback, Nicholas J Krebs, J Kent Leach, David J Mooney, Stanley W Ashley, Joseph P Vacanti, Edward E Whang

  Biomaterials. 08/2008; 29(19):2884-90.

  Our group has previously created a functional neointestine that is capable of restoring absorptive function. However, the endogenous level of vascular endothelial growth factor (VEGF) is markedlyOur group has previously created a functional neointestine that is capable of restoring absorptive function. However, the endogenous level of vascular endothelial growth factor (VEGF) is markedly reduced in the construct compared to native bowel. Therefore, we wanted to locally deliver VEGF in a sustained fashion to upregulate angiogenesis in the neointestine. Rat recombinant VEGF was encapsulated in poly(lactide-co-glycolide) microspheres by a double emulsion method. Release kinetics and bioactivity were determined in vitro. Tissue-engineered intestine was generated by seeding donor neonatal rat intestinal organoid units onto a biodegradable polyglycolic acid scaffold along with VEGF-containing or empty microspheres, and wrapped in the omentum of recipient rats. After 4 weeks, the neointestinal cysts were analyzed for morphometry, VEGF levels, epithelial proliferation, and capillary density. Sustained release of biologically active VEGF was confirmed by in vitro studies. Intestinal constructs with VEGF microspheres were significantly larger than those containing empty microspheres. Tissue VEGF levels were significantly higher in neointestine loaded with encapsulated VEGF compared to those without growth factor. Epithelial cellular proliferation and capillary density were significantly increased in the VEGF-containing neointestinal constructs compared to empty constructs. Tissue-engineered intestine responds to sustained delivery of VEGF by upregulating microvasculature and epithelial proliferation.