Vascular Patch Research Articles

An entropy–elastic gelatin-based hydrogel system

Gelatin is a non-immunogenic and degradable biopolymer, which is widely applied in the biomedical field e.g. for drug capsules or as absorbable hemostats. However, gelatin materials present limited and hardly reproducible mechanical properties especially in aqueous systems, particularly caused by the uncontrollable partial renaturation of collagen-like triple helices. Therefore, mechanically demanding applications for gelatin-based materials, such as vascular patches, i.e. hydrogel films that seal large incisions in vessel walls, and for induced autoregeneration, are basically excluded if this challenge is not addressed. Through the synthesis of a defined chemical network of gelatin with hexamethylene diisocyanate (HDI) in DMSO, the self-organization of gelatin chains could be hindered and amorphous gelatin films were successfully prepared having Young's moduli of 60–530 kPa. Transferring the crosslinking reaction with HDI and, alternatively, ethyl lysine diisocyanate (LDI), to water as reaction medium allowed the tailoring of swelling behaviour and mechanical properties by variation of crosslinker content while suppressing the formation of helices. The hydrogels had Young's moduli of 70–740 kPa, compressive moduli of 16–48 kPa, and degrees of swelling of 300–800 vol%. Test reactions investigated by ESI mass spectrometry allowed the identification and quantification of reaction products of the crosslinking reaction. The HDI crosslinked networks were stabilized by direct covalent crosslinks (ca. 10 mol%), supported by grafting (50 mol%) and blending of hydrophobic oligomeric chains. For the LDI-based networks, less crosslinked (3 mol%) and grafted species (5 mol%) and much higher amounts of oligomers were observed. The adjustable hydrogel system enables the application of gelatin-based materials in physiological environments.

Enhanced Hematovascular Contribution of SCL 3′ Enhancer Expressing Fetal Liver Cells Uncovers Their Potential to Integrate in Extramedullary Adult Niches

Fetal liver (FL) hematopoietic progenitors have superior blood engraftment competence compared with adult bone marrow (BM), however less is known about FL in vivo vascular capacity. Here we show in transplantation assays that FL cells possess enhanced vascular endothelial potential compared with adult bone marrow. We generated high-level hematopoietic chimeras using donor cells from mice transgenic for the stem cell leukaemia 3' enhancer human placental alkaline phosphatase (SCL3'Enh-PLAP) reporter construct, active in vascular endothelium, and blood progenitor and stem cells. Long-term lineage tracing analysis revealed PLAP(+) vascular-like patches in FL-derived chimeras, whereas adult BM-derived chimeras presented only rare and scattered PLAP(+) cells. PLAP(+) vascular-like patches were formed following transplantation into both newborn and adult recipient mice, although their frequency was reduced in adult recipients. Confocal analysis of multiple labeled tissues revealed that whereas most liver and heart PLAP(+) vascular patch-associated cells were endothelial, PLAP(+) vascular patches in the kidney contained endothelial, hematopoietic, and putative hemangioblastic cells. Moreover, fluorescence-activated cell sorting assays showed that only FL PLAP(bright+) donor cells can generate PLAP(+) vascular patches upon transplantation. Taken together, these data demonstrate superior vascular contribution potential of FL cells, and not only provide new insights into the developmental pathways controlling endothelial development but also may prove informative when addressing the mechanisms involved in vascular regeneration and hemangiogenic recovery in a clinical context.

Permacol (Porcine Dermal Collagen) and Alloderm (Acellular Cadaveric Dermis) as a Vascular Patch Repair for Common Carotid Arteriotomy in a Rabbit Model

Occult injuries to arteries are common in trauma and evolution of their repair has been observed throughout military conflicts. Currently, autogenous vein and polytetrafluoroethylene (PTFE) are used as patch agents for arterial trauma. However, suitable vein is often lacking in multitrauma patients, and PTFE is prone to infection in the contaminated combat wound. The purpose of this study is to evaluate Permacol, porcine dermal collagen, and Alloderm, acellular cadaveric dermis, as suitable alternatives to PTFE with the potential benefit of being used in contaminated wounds. A New Zealand White rabbit common carotid arteriotomy model was used to compare Permacol (n = 12), Alloderm (n = 11), and PTFE (n = 13) for patch repair. Thrombin generation was examined using an enzyme-linked immunosorbent assay for thrombin-antithrombin complex. Histological samples were taken to analyze vessel lumen area, vessel diameter, intimal thickness, and medial thickness. Pathological examinations were made to compare rates of intimal hyperplasia, aneurysm, patency, and thrombus formation. The Permacol group showed equivalent rates of thrombus, aneurysm, and patency compared with PTFE. Increased lumen area was seen in the Permacol group, 0.344 mm2 (p = 0.02) compared with the PTFE group, 0.204 mm2. Permacol also had decreased incidence of intimal hyperplasia compared with PTFE, 50.0% versus 92% (p < 0.05). Alloderm had increased rates of aneurysm formation, 63.6% (p = 0.004) compared with PTFE, 0.0%, and Permacol groups, 8.3%. Alloderm also had increased intimal thickness through the patch, 0.076 mm (p = 0.18), compared with PTFE, 0.026 mm, and Permacol groups, 0.024 mm. Vessel diameter through the patch showed the Alloderm group, 1.87 mm (p = 0.004), was significantly larger than both the Permacol, 1.41 mm, and PTFE groups, 1.28 mm. Furthermore, Alloderm showed leukocyte migration around the patch. Enzyme-linked immunosorbent assay for thrombin-antithrombin complex was only elevated for PTFE in the 7-day postoperative measurement but was not statistically different from the other groups. Permacol has characteristics to be an effective alternative for PTFE for patch arteriotomy repair in our rabbit model. Futher studies need to be conducted to investigate the potential of Permacol in vascular trauma. Alloderm is not a suitable alternative to PTFE for patch arteriotomy repair.

Polytetrafluoroethylene Patch Venoplasty for Outflow Reconstruction in Living Donor Liver Transplantation: Two Case Reports

Outflow obstruction may lead to liver congestion and eventual graft failure after living donor liver transplantation. Various methods of venoplasty provide wider outflow tracts. Most series have suggested use of autologous or allogenic grafts for patch venoplasty. We used a polytetrafluorethylene patch in two patients. Both showed good patency of the outflow tract at Doppler ultrasonography at 7 months and 4 months posttransplantation. A polytetrafluoroethylene patch may be a good alternative when no other autologous or allogeneic vascular patch is available or when the situation is critical.

Novel tissue-engineered vascular patches based on decellularized canine aortas and their recellularization in vitro

Decellularized allo- or xenogeneic vascular grafts have been found to give more promising results than some biodegradable synthetic polymers. However, owing to absence of well-organized cells, especially confluent endothelial cells, their long-term patency is limited. Seeding vessel-originated cells on these grafts may overcome the deficiency. In this study, canine aortas were decellularized and cross-linked. 4′,6-Diamidino-2-phenylindole (DAPI) and Masson’ trichrome staining showed complete removal of cell debris, while structure integrity of extracellular matrix (ECM) was remained. Human umbilical vein endothelial cells (HUVECs) and human umbilical artery smooth muscle cells (HUASMCs) were seeded on these decellularized aorta patches in three manners, ECs alone (EC/O), SMCs alone (SMC/O) and ECs on SMCs layer (EC/SMC). In EC/O and SMC/O, scanning electron microscopy (SEM) examination indicated both cells could form confluent layers on the decellularized patches when seeded at high density, but their morphology and alignment changed with seeding density. In EC/SMC, ECs could grow well on SMCs layer, but their morphology, alignment, and confluence degree were deeply influenced by the density of SMCs beneath.

Late Presentation of an Infected Carotid Patch as a Superficial Wound Nodule

Infection of a vascular patch is an uncommon complication of carotid endarterectomy. Case report and review of the pertinent English-language literature. A 71 year-old woman with a carotid patch infection presented with a superficial wound nodule and no false aneurysm. Diagnosis thus was delayed but was confirmed eventually with magnetic resonance imaging. Excision and saphenous vein bypass was successful. The rare complication of infection of a polyester vascular patch is described with recommendations for early diagnosis and definitive therapy.

Human vascular smooth muscle cells and endothelial cells cocultured on polyglycolic acid (70/30) scaffold in tissue engineered vascular graft

Current prosthetic, small diameter vascular grafts showing poor long term patency rates have led to the pursuit of other biological materials. Biomaterials that successfully integrate into surrounding tissue should match not only the mechanical properties of tissues, but also topography. Polyglycolic acid (70/30) has been used as synthetic grafts to determine whether human vascular smooth muscle cells and endothelial cells attach, survive and secrete endothelin and 6-keto-prostaglandin F1alpha (6-keto-PGF1alpha). Endothelial cells and smooth muscle cells were isolated from adult human great saphenous vein. They were seeded on polyglycolic acid scaffold in vitro separately to grow vascular patch (Groups A and B respectively) and cocultured in vitro to grow into vascular patch (Group C). Smooth muscle cells and endothelial cells were identified by immunohistochemical analysis and growth of cells on polyglycolic acid was investigated using scanning electron microscopy. The levels of endothelin and 6-keto-PGF1alpha in the culturing solutions were examined by radioimmunology to measure endothelial function. Seed smooth muscle cells adhered to polyglycolic acid scaffold and over 28 days grew in the interstices to form a uniform cell distribution throughout the scaffold. Then seed endothelial cells formed a complete endothelial layer on the smooth muscle cells. The levels of endothelin and 6-keto-prostaglandin F1 alpha in the culturing solution were (234 +/- 29) pg/ml and (428 +/- 98) pg/ml respectively in Group C and (196 +/- 30) pg/ml and (346 +/- 120) pg/ml in Group B; both significantly higher than in Groups A and D (blank control group, all P < 0.05). Cells could be grown successfully on polyglycolic acid and retain functions of secretion. Our next step is to use human saphenous vein smooth muscle cells and endothelial cells to grow tubular vascular grafts in vitro.

P160: A simple intra-aortic shunt restores hemodynamics and prevents paralysis in an ovine model to test tissue engineered vascular patches

Introduction: Recent advances in the engineering of novel tissues for vascular patches and heart valves require pre-clinical in-vivo testing. Although many animal models are available, the United States Food and Drug Administration highly suggests testing cardiovascular tissue in sheep as an accelerated model of calcification. However, sheep are particularly prone to spinal cord ischemia and subsequent paralysis during aortic cross clamping, which is often required for the implantation procedure. We report the use and hemodynamic effects of a simple intra-aortic shunt to facilitate the implantation of tissue engineered vascular patches in the descending thoracic aorta of sheep. Methods: After clamping the descending thoracic aorta, a 6cm longitudinal aortotomy was made at the level of the 6th intercostal space. A shunt consisting of a 9 cm long heparin bonded 6.35 mm (internal diameter) polyvinyl tube was inserted through the aortotomy into the aorta to provide blood flow across the operative site. Blood pressure and flow in the distal aorta were measured continuously with an indwelling femoral artery catheter and a Triton ultrasonic aortic flow probe. The hemodynamic effects were measured in seven 45 - 55 kg Suffolk sheep. This shunt was then used to implant decellularized pulmonary artery patches into 25 animals. Multiple means were compared by ANOVA with Scheffe post hoc analysis. Results: The mean aortic pressure distal to the shunt prior to clamping the aorta was 86.4 ± 4.6 mmHg. Occlusion of the aorta reduced the distal mean aortic pressure to 1.79 ± 0.4 mmHg (p < 0.001) and opening the intra-aortic shunt restored the distal mean aortic pressure to 67.9 ± 7.3 mmHg (p = 0.053). Blood flow in the distal aorta was 2.35 ± 0.37 L/minutes at baseline and was reduced to -0.01 ± 0.01 L/minutes (p < 0.001) with the aorta cross clamped. When the shunt was opened, distal aortic flow returned to 2.49 ± 0.36 L/minute (p = 0.945). Prior to instituting this shunt, 2 of 2 sheep developed immediate paralysis of the hind legs following the implantation of a vascular patch in the descending thoracic aorta. Use of this shunt prevented hind leg paralysis in all 24 animals surviving the procedure. Early in this series, one animal died intraoperatively from an aortic injury related to removing the shunt. Ten animals were survived for 4 weeks and 13 were survived for 6 months without complication. A single animal died 61 days after surgery from a ruptured mycotic aneurysm. Conclusions: A simple intra-aortic shunt was effective in restoring blood pressure and flow in the aorta distal to the operative site and prevented hind leg paralysis associated with aortic clamping. Moreover, this shunt was easy to insert and remove and does not require additional aortotomies.

Venous outflow reconstruction with surgically reopened obliterated umbilical vein in domino liver transplantation

Venous outflow reconstruction with surgically reopened obliterated umbilical vein in domino liver transplantation

Endothelial Progenitor and Mesenchymal Stem Cell–Derived Cells Persist in Tissue-Engineered Patch In Vivo: Application of Green and Red Fluorescent Protein–Expressing Retroviral Vector

An unresolved question regarding tissue-engineered (TE) cardiac valves and vessels is the fate of the transplanted cells in vivo. We have developed a strategy to track the anatomic location of seeded cells within TE constructs and neighboring tissues using a retroviral vector system encoding green and red fluorescent proteins (GFPs and RFPs, respectively) in ovine circulating endothelial progenitor cells (EPCs) and bone marrow-derived mesenchymal stem cells (BMSCs). We demonstrate that stable transduction ex vivo with high-titer Moloney murine leukemia virus-based retroviral vector yields transduction efficiency of greater than 97% GFP(+) EPC- and RFP(+) mesenchymal stem cell (MSC)-derived cells. Cellular phenotype and transgene expression were also maintained through 25 subsequent passages. Using a retroviral vector system to distinguish our pre-seeded cells from tissue-resident progenitor cells and circulating endothelial and marrow-derived precursors, we simultaneously co-seeded 2 x 10(6) GFP(+) EPCs and 2 x 10(5) RFP(+) MSCs onto the TE patches. In a series of ovine pulmonary artery patch augmentation studies, transplanted GFP(+) EPC- and RFP(+) MSC-derived cells persisted within the TE patch 7 to 14 days after implantation, as identified using immunofluorescence. Analysis showed 81% luminal coverage of the TE patches before implantation with transduced cells, increasing to 96% at day 7 and decreasing to 67% at day 14 post-implantation. This suggests a temporal association between retroviral expression of progenitor cells and mediating effects of these cells on the physiological remodeling and maturation of the TE constructs. To our knowledge, this is the first cardiovascular tissue-engineering in vivo study using a double-labeling method to demonstrate a direct evidence of the source, persistence, and incorporation into a TE vascular patch of co-cultured and simultaneously pre-seeded adult progenitor cells.

Preliminary experience with tissue engineering of a venous vascular patch by using bone marrow–derived cells and a hybrid biodegradable polymer scaffold

Currently available synthetic polymer vascular patches used in cardiovascular surgery have shown serious shortcomings, including thrombosis, calcification, infection, and lack of growth potential. These problems may be avoided by vascular patches tissue-engineered with autologous stem cells and biodegradable polymeric materials. The objective of this study was to develop a tissue-engineered vascular patch by using autologous bone marrow-derived cells (BMCs) and a hybrid biodegradable polymer scaffold. Hybrid biodegradable polymer scaffolds were fabricated from poly(lactide-co-epsilon-caprolactone) (PLCL) copolymer reinforced with poly(glycolic acid) (PGA) fibers. Canine bone marrow mononuclear cells were induced in vitro to differentiate into vascular smooth muscle cells and endothelial cells. Tissue-engineered vascular patches (15 mm wide x 30 mm long) were fabricated by seeding vascular cells onto PGA/PLCL scaffolds and implanted into the inferior vena cava of bone marrow donor dogs. Compared with PLCL scaffolds, PGA/PLCL scaffolds exhibited tensile mechanical properties more similar to those of dog inferior vena cava. Eight weeks after implantation of vascular patches tissue-engineered with BMCs and PGA/PLCL scaffolds, the vascular patches remained patent with no sign of thrombosis, stenosis, or dilatation. Histological, immunohistochemical, and scanning electron microscopic analyses of the retrieved vascular patches revealed regeneration of endothelium and smooth muscle, as well as the presence of collagen. Calcium deposition on tissue-engineered vascular patches was not significantly different from that on native blood vessels. Immunofluorescent double staining confirmed that implanted BMCs survived after implantation and contributed to regeneration of endothelium and vascular smooth muscle in the implanted vascular patches. This study demonstrates that vascular patches can be tissue-engineered with autologous BMCs and hybrid biodegradable polymer scaffolds.

A Randomized Trial of Synthetic Patch versus Direct Primary Closure in Carotid Endarterectomy

To define whether or not direct microscopic closure with or without the use of a vascular patch is advantageous in terms of clinical outcome and late vessel occlusion rates after microsurgical carotid endarterectomy. Three hundred thirty-eight elective carotid endarterectomies in 315 patients were randomized to direct arteriotomy or closure with a polyester collagen-coated vascular patch. Ten procedures did not follow the randomization process because of technical difficulties and were excluded. Vessel patency (duplex ultrasound) and outcome were assessed during and immediately after surgery and at 4 and 12 months after surgery. Four-month ultrasound assessment (n = 321) identified five occluded vessels: two in the patch group (n = 149) and three in the direct closure group (n = 172). Six patients in the patch group had died or were significantly disabled at 4 months, compared with five in the direct closure group. At the 12-month assessment (n = 313), eight vessels had occluded: five from the patched group (n = 146) and three from the direct closure group (n = 167). Eight patients in the patch group had died or were significantly disabled, compared with four in the direct closure group. No statistically significant difference between the two groups in terms of vessel occlusion, morbidity, or mortality was seen (P > 0.1). No difference in vessel patency and clinical outcome has been identified after microscopic patch angioplasty and direct arteriotomy repair. The authors conclude that there is no benefit from the routine use of patch angioplasty in microscopic carotid endarterectomy.

Trasplante renal de donante vivo: implante renal y sus variantes

The objective of this paper is to review the various surgical techniques for living donor kidney transplantation. We perform a bibliographic review adding our experience in living kidney transplantation. We present various techniques indicating which one is the most appropriate for each case. We should promote living door kidney transplantation if we want to increase the number of transplants performed. It is a complex transplant because the graft lacks of vascular patches; there are various surgical techniques that we can choose depending on the case.

Pseudoaneurysm formation in a subset of patients with small intestinal submucosa biologic patches after carotid endarterectomy

The carotid artery is frequently patched after carotid endarterectomy (CEA) to minimize the risks of early postoperative thrombosis and late recurrent stenosis. The small intestinal submucosa (SIS) patch is a biologic vascular patch derived from porcine small intestine. It is composed primarily of cell-free collagen and other extracellular matrix constituents that act as a scaffold for host cell deposition. In May 2001, we began an investigational trial of SIS patches in 76 patients undergoing patch angioplasty of the carotid artery after CEA. No adverse events related to the patches were observed in the first 69 patients implanted with an SIS patch. However, in late 2002, seven patients were found to have asymptomatic pseudoaneurysms (PSA) by duplex imaging < or =10 weeks after their CEAs. The trial was immediately suspended. The PSAs were treated by surgical resection with vein grafting in two patients and placement of covered endoluminal stents in four patients. One patient is being followed as the PSA is small and has remained stable. Histopathologic examination of the SIS patch explanted from one of the surgically treated patients demonstrated the presence of actin-positive myofibroblasts or smooth muscle cells. Extensive mechanical testing of the SIS material from the two material lots associated with PSAs demonstrated thinner and more variable physical characteristics compared with control device lots. Biologic patches that undergo active remodeling in the carotid artery require greater thickness than was anticipated to decrease wall stress and suture hole elongation. Patches exceeding this minimum thickness will be required to ensure the safety of new SIS patch designs for vascular operations.

Using Fascia Lata to Treat Infective Aortic False Aneurysm

In patients with infective aortic false aneurysms, repair using artificial materials is in danger of becoming an additional focus for infection. We used harvested autologous fascia lata as a vascular patch in such operations on 2 patients with infected mediastinal false aneurysm after coronary artery bypass surgery. These patients have not had any recurrences of mediastinitis and false aneurysm for 4 to 6 years after the operations.

INVITED COMMENTARY

This study describes another important attempt to overcome the limitations of currently available biomaterials in cardiac surgery. Decellularization of biomaterials, in this case ovine pulmonary patches, is thought to reduce antigenicity. However the efficiency of various protocols may differ importantly. In this study a combined anionic–enzymatic protocol is used and cells were effectively removed. Three groups of vascular patches, cryopreserved, cryopreserved–decellularized, and decellularized were implanted as vascular patches in the descending aorta and pulmonary artery in juvenile sheep for 10 and 20 weeks.

The morphology and vasculature of the respiratory organs of terrestrial hermit crabs ( Coenobita and Birgus): gills, branchiostegal lungs and abdominal lungs

The morphology and vasculature of the respiratory organs of the terrestrial coenobitids were studied using light microscopy, TEM, SEM and corrosion casting. The gills of Coenobita and Birgus are modified for air-breathing but are reduced in number and size and have a comparatively small surface area. The branchiostegal lungs of Coenobita (which live in gastropod shells) are very small but are well vascularized and have a thin blood/gas barrier. Coenobita has developed a third respiratory organ, the abdominal lung, that is formed from highly vascularized patches of very thin and intensely-folded dorsal integument. Oxygenated blood from this respiratory surface is returned to the pericardial sinus via the gills (in parallel to the branchiostegal circulation). Birgus, which does not inhabit a gastropod shell, has developed a highly complex branchiostegal lung that is expanded laterally and evaginated to increase surface area. The blood/gas diffusion distance is short and oxygenated blood is returned directly to the pericardium via pulmonary veins. We conclude that the presence of a protective mollusc shell in the terrestrial hermit crabs has favoured the evolution of an abdominal lung and in its absence a branchiostegal lung has been developed.

Blood vessel tissue engineering: seeding vascular smooth muscle cells and endothelial cells sequentially on biodegradable scaffold in vitro

To evaluate the effect of seeding vascular smooth muscle cells and endothelial cells sequentially on biodegradable scaffold in vitro. Venous endothelial cells and smooth muscle cells of artery were isolated from the umbilical cord of newborn and cultured in vitro. The cultured arterial smooth muscle cells and cultured endothelial cells were seeded on the polyglycolic acid and polylactide (PLGA) nonwoven mesh as tissue scaffolds respectively (group A and group B). And cultured endothelial cells were seeded on the scaffold already seeded with smooth muscle cells sequentially to construct vascular patch (group C). One month after cultivation the patches of the 3 groups underwent HE staining and microscopic examination and scanning electron microscopy. Immunohistochemistry was used to examine the existence of actin and factor VIII-related antigen, secreted by endothelial cells, in the cells. The levels of endothelin and 6-Keto-PGF1alpha in the culture solution were examined by means of radioimmunology so as to measure the endothelial function. Pure culture solution was used as blank control (group D). Microscopy showed that cells were fused into patch in the group C. HE staining showed that the smooth muscle cells were embedded into the PLGA scaffold and grew in multiple layers covered by a layer of endothelial cells on the surface. The types of cells could be identified by immunohistochemical procedure. The levels of endothelin and 6-Keto-PGF1alpha in the culture solution were 229 pg/ml +/- 34 pg/ml and 402 pg/ml +/- 108 pg/ml respectively in the group C, and 200 pg/ml +/- 31 pg/ml and 336 pg/ml +/- 121 pg/ml in the group B, both significantly higher than those in the groups A and D (blank control group, all P < 0.05 or P < 0.05). Tissue engineering blood vessel with normal morphological and functional characters to a certain degree can be constructed through seeding cultured vascular smooth muscle cells and endothelial cells sequentially on PLGA scaffold.

Biodegradable polymer with collagen microsponge serves as a new bioengineered cardiovascular prosthesis

ObjectiveBiodegradable materials with autologous cell seeding have attracted much interest as potential cardiovascular grafts. However, pretreatment of these materials requires a complicated and invasive procedure that carries the risk of infection. To avoid these problems, we sought to develop a biodegradable graft material containing collagen microsponge that would permit the regeneration of autologous vessel tissue. The ability of this material to accelerate in situ cellularization with autologous endothelial and smooth muscle cells was tested with and without precellularization. MethodsPoly(lactic-co-glycolic acid) as a biodegradable scaffold was compounded with collagen microsponge to form a vascular patch material. These poly(lactic-co-glycolic acid)–collagen patches with (n = 10) or without (n = 10) autologous vessel cellularization were used to patch the canine pulmonary artery trunk. Histologic and biochemical assessments were performed 2 and 6 months after the implantation. ResultsThere was no thrombus formation in either group, and the poly(lactic-co-glycolic acid) scaffold was almost completely absorbed in both groups. Histologic results showed the formation of an endothelial cell monolayer, a parallel alignment of smooth muscle cells, and reconstructed vessel wall with elastin and collagen fibers. The cellular and extracellular components in the patch had increased to levels similar to those in native tissue at 6 months. ConclusionsThe poly(lactic-co-glycolic acid)–collagen microsponge patch with and without precellularization showed good histologic findings and durability. This patch shows promise as a bioengineered material for promoting in situ cellularization and the regeneration of autologous tissue in cardiovascular surgery.

Vascular patches tissue-engineered with autologous bone marrow-derived cells and decellularized tissue matrices

Synthetic polymer vascular patches used in cardiovascular surgery have shortcomings such as thrombosis, intimal hyperplasia, calcification, infection, and no growth potential. Tissue-engineered vascular patches using autologous vascular cells may solve these problems. In this study, we developed a tissue-engineered vascular patch using autologous bone marrow-derived cells (BMCs) and decellularized tissue matrices. Vascular smooth muscle cells and endothelial cells were differentiated from bone marrow mononuclear cells in vitro. Tissue-engineered vascular patches were fabricated by seeding these cells onto decellularized canine inferior vena cava matrices and implanted into the inferior vena cava of dogs. Three weeks after implantation, the tissue-engineered vascular patches were patent with no sign of thrombus formation. Histological, immunohistochemical, and electron microscopic analyses of the vascular patches retrieved 3 weeks after implantation revealed regeneration of endothelium and smooth muscle and the presence of collagen and elastin. BMCs labeled with a fluorescent dye prior to implantation were detected in the retrieved vascular patches, indicating that the BMCs survived after implantation and contributed to the vascular tissue regeneration. This study demonstrates that vascular patches can be tissue-engineered with autologous BMCs and decellularized tissue matrices.