Microarterial synthetic graft repair: interstitial cellular components

Microvessel manifold for perfusion and media exchange in three-dimensional cell cultures

Integrating a perfusable microvasculature system in vitro is a substantial challenge for "on-chip" tissue models. We have developed an inclusive on-chip platform that is capable of maintaining laminar flow through porous biosynthetic microvessels. The biomimetic microfluidic device is able to deliver and generate a steady perfusion of media containing small-molecule nutrients, drugs, and gases in three-dimensional cell cultures, while replicating flow-induced mechanical stimuli. Here, we characterize the diffusion of small molecules from the perfusate, across the microvessel wall, and into the matrix of a 3D cell culture.

Vascular endothelial growth pattern of endochondral bone graft in the presence of demineralized intramembranous bone matrix--quantitative analysis

OBJECTIVE

To determine the timely ingrowth of new blood vessels of composite endochondral (EC) bone and demineralized bone matrix (DBM) prepared from intramembranous (IM) origin (EC-DBM(IM)) and to compare it with EC bone graft alone.

DESIGN

Thirty-two rabbits with 32 critical-size (10 x 5 mm), full-thickness bony defects in rabbit parietal bone were divided into two groups: composite EC-DBM(IM) group-implanted with composite autogenous EC bone and DBM(IM); EC bone group-implanted with EC bone alone. Two rabbits from each group were sacrificed-1, 2, 3, 4, 5, 6, 7, and 14 days after grafting. Neovascularization was assessed by immunohistochemical staining with antihuman angiogenesis-related endothelial cell antibodies (EN 7/44). Quantitative analysis of neovascularization, represented by percentage area of positive immunohistochemical staining, was performed on 320 sections of the experimental groups by a computer-assisted image analyzer.

RESULTS

Positive immunohistochemical staining was first identified on day 2 post grafting for the composite EC-DBM(IM) group in comparison with day 4 in the EC bone graft group. The composite EC-DBM(IM) bone graft group showed earlier and almost 100% more neovascularization when compared with the EC bone graft group.

CONCLUSION

DBM(IM) enhances healing and integration of EC bone graft by enhancing vascularization as well as increasing the amount of new blood vessels formed. In clinical cases in which EC autogenous bone is used to graft a large defect such as in cleft palate and craniofacial surgery, DBM(IM) should allow better integration and healing of the EC bone graft to the host bone.

Arterial autografts and PTFE vascular microprostheses: similarities in the healing process

A comparative study has been carried out dealing with the vascular healing process in two experimental vascular graft models to determine the differences or similarities between the two. One of the models consisted of the use of arterial autografts and the other of the implantation of vascular microprostheses of polytetrafluoroethylene (PTFE). The common iliac artery of female Sprague-Dawley rats was used. The length of the grafts in both models was 5 mm. A microsurgical technique was employed, and anticoagulant and antibiotic therapies were not used. The results were studied using light microscopy, transmission and scanning electron microscopies, autoradiography, and immunohistochemistry. A patency of 100% was obtained in the arterial autografts, and 87.6% in the PTFE implants. The histopathological findings were as follows: a) the mechanisms of immediate postgrafting response were similar, with marked presence of fibrin and platelet deposition in the form of a nonthrombogenic monolayer; b) a "neoadventitia" formed over the implant in both models; c) the endothelialisation was complete in both types of grafts 2 to 3 weeks after implantation; d) an intimal hyperplastic response appeared in both, although at different times (in the first week in the autografts and at one month with the PTFE); e) white cell accumulation was significantly greater on the PTFE luminal surface than on the autograft. The intimal hyperplasia was formed mainly by secretory myocytes in the autografts, while in the PTFE implants, fibrosis predominated.

Expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) on proliferating vascular endothelial cells in diabetic epiretinal membranes

The present study demonstrated the expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1), the proliferating status of the neovascular endothelial cells, and the activation of vascular endothelial cells bearing the two cell adhesion molecules in diabetic epiretinal membranes by using double immunofluorescence and APAAP techniques. The results showed that ICAM-1 was detected in 36 out of 40 (90%) proliferative diabetic retinopathy epiretinal membranes, VCAM-1 was found in 32 out of 40 cases (80%); in 21 out of 26 (81%) vascularised membranes the endothelial cells of the new vessels in the membranes were still in a proliferative stage (positive for proliferating endothelial cell marker EN 7/44) and, further, in 20 out of 26 cases (77%) ICAM-1 was detected on the proliferating endothelial cells and VCAM-1 was found in 21 cases (81%). The expression of cell adhesion molecules, especially ICAM-1 and VCAM-1 in diabetic epiretinal membranes suggests that cell to cell interactions may play a significant role in the development of PDR membranes. In particular, the expression of ICAM-1 and VCAM-1 on proliferating endothelial cells indicates the activation of these cells, which is the first critical step for lymphocyte/endothelial cell interactions and the initiation of immune responses. The significance of proliferating status of the neovascularisation in the membranes may be related to the clinical course and prognosis of the disease.