Novel Vascular Graft Grown Within Recipient’s Own Peritoneal Cavity

Abstract

—A method by which to overcome the clinical symptoms of atherosclerosis is the insertion of a graft to bypass an artery blocked or impeded by plaque. However, there may be insufficient autologous mammary artery for multiple or repeat bypass, saphenous vein may have varicose degenerative alterations that can lead to aneurysm in high-pressure sites, and small-caliber synthetic grafts are prone to thrombus induction and occlusion. Therefore, the aim of the present study was to develop an artificial blood conduit of any required length and diameter from the cells of the host for autologous transplantation. Silastic tubing, of variable length and diameter, was inserted into the peritoneal cavity of rats or rabbits. By 2 weeks, it had become covered by several layers of myofibroblasts, collagen matrix, and a single layer of mesothelium. The Silastic tubing was removed from the harvested implants, and the tube of living tissue was everted such that it now resembled a blood vessel with an inner lining of nonthrombotic mesothelial cells (the “intima”), with a “media” of smooth muscle–like cells (myofibroblasts), collagen, and elastin, and with an outer collagenous “adventitia.” The tube of tissue (10 to 20 mm long) was successfully grafted by end-to-end anastomoses into the severed carotid artery or abdominal aorta of the same animal in which they were grown. The transplant remained patent for at least 4 months and developed structures resembling elastic lamellae. The myofibroblasts gained a higher volume fraction of myofilaments and became responsive to contractile agonists, similar to the vessel into which they had been grafted. It is suggested that these nonthrombogenic tubes of living tissue, grown in the peritoneal cavity of the host, may be developed as autologous coronary artery bypass grafts or as arteriovenous access fistulae for hemodialysis patients.

The Fibrotic Response to Implanted Biomaterials: Implications for Tissue Engineering

“…By day 7 a distinct capsule of round cells and extracellular matrix (ECM) had formed, and by day 14 cells had elongated and organised into multilayered strata within a fibrillar matrix. Ultrastructurally, these elongated cells had the characteristics of myofibroblasts and contained large amounts of rough endoplasmic reticulum and bundles of peripherally distributed myofilaments (Campbell & Ryan, 1983;Campbell et al, 1999). A layer of mesothelial cells was also observed to cover the developing capsule.…”

“…However despite intensive testing, the lack of compliance/strength of the resulting tissue, as well as the absence of an endothelial lining, resulted in unacceptably high rates of thrombosis, dilatation and aneurysm (Conte, 1998). More recently, our laboratory and others have used the peritoneal cavity as a 'bioreactor' to produce autologous tissue for replacement/repair of arteries (Campbell et al, 1999Chue et al, 2004) and other hollow smooth muscle organs, specifically bladder, uterus, vas deferens and urethra (Gu et al, 2009). De Visscher and co-workers used a similar technique to pre-seed acellular matrix scaffolds from bovine pericardium for use as tissue engineered heart valves (De Visscher et al, 2007, 2008Vranken et al, 2008) while Hayashida et al (2007) reported satisfactory function and mechanical properties for 'biovalves' prepared by embedding synthetic scaffolds subcutaneously for 4 weeks.…”

Tissue Engineering and Regenerative Strategies to Replicate Biocomplexity of Vascular Elastic Matrix Assembly

“…However, this will require an understanding of phenotypic differences between vascular and such nonvascular SMC types and an investigation into the possibility of retraining these differentiated cell types to assume a phenotype more typical of VSMCs, while retaining their own inherent high elastogenic capacity. Recently, Campbell et al [117][118][119] reported on recruitment of macrophage-like cells from peritoneal fluid onto silastic tubes implanted within peritoneal cavities of rats and their production of a fibrous tissue capsule. Although the everted tubular tissue capsule exhibited distinct circumferential layers resembling the vascular tunics (i.e., a luminal mesothelium, an outer collagenous layer, and a layer of myofibroblasts in the middle), little elastin was observed in these constructs.…”

α1 adrenergic receptor agonist, phenylephrine, actively contracts early rat rib fracture callus ex vivo

“…3 Seven day calluses were used for force measurement as such calluses are fibrous in nature and ideal for measurement of active force production. 3 [21][22][23][24] KH solution had the following composition (mM): NaCl 135; KCl 5; MgCl 2 3; NaH 2 PO 4 0.8; HEPES 10; calcium (Ca 2þ ) 1.2; glucose 5. Solution temperature was 228C and its stable pH was stable at 7.4 for a period of at least 6 h.…”