Electrospun PHEA-PLA/PCL Scaffold for Vascular Regeneration: A Preliminary in Vivo Evaluation.

BACKGROUND: There is increasing interest in the development of vessel substitutes, and many studies are currently focusing on the development of biodegradable scaffolds capable of fostering vascular regeneration. We tested a new biocompatible and biodegradable material with mechanical properties similar to those of blood vessels. METHODS: The material used comprises a mixture of α,ß-poly(N-2-hydroxyethyl)-d,l-aspartamide (PHEA) and polylactic acid (PLA), combined with polycaprolactone (PCL) by means of electrospinning technique. Low-molecular-weight heparin was also linked to the copolymer. A tubular PHEA-PLA/PCL sample was used to create an arteriovenous fistula in a pig model with the use of the external iliac vessels. The flow was assessed by means of Doppler ultrasound examination weekly, and 1 month after the implantation we removed the scaffold for histopathologic evaluation. RESULTS: The implants showed a perfect leak-proof seal and adequate elastic tension to blood pressure. About ∼3 weeks after the implantation, Doppler examination revealed thrombosis of the graft, so we proceeded to its removal. Histologic examination showed chronic inflammation, with the presence of foreign body cells and marked neovascularization. The material had been largely absorbed, leaving some isolated spot residues. CONCLUSIONS: The biocompatibility of PHEA-PLA/PCL and its physical properties make it suitable for the replacement of vessels. In the future, the possibility of functionalizing the material with a variety of molecules, to modulate the inflammatory and coagulative responses, will allow obtaining devices suitable for the replacement of native vessels.

A comparison of 4 methods of data presentation for lysosomal enzyme activity in gingival crevicular fluid.

In previous studies, we have emphasized the importance of considering the methods used for analysis of gingival crevicular fluid (GCF). This study evaluated 4 different approaches for data presentation of lysosomal enzyme activity in GCF. GCF was collected from patients displaying at least 2 mm of clinical attachment loss at a minimum of 3 sites in the mouth (DA), and patients who did not display clinical attachment loss of 2 mm or more at any site in the mouth (DI), during a 3-month interval following entry into a longitudinal trial. GCF was collected by the timed intrasulcular placement of precut filter paper strips. 16 to 28 individual GCF samples were collected from each patient. The lysosomal enzymes studied were B-glucuronidase (BG) and arylsulfatase. The mean values for the DA and DI groups at baseline and 3 months are reported. The results indicate that when the data is expressed as total enzyme activity (unit activity) per 30-s collection (UA) or UA x GCF volume (microliter) per mm of probing depth, the DA group demonstrated significantly greater mean values than the DI group at baseline and 3 months. In contrast, when the data was expressed as concentration (UA/microliter), or UA per mm of probing depth, differences between the DA and DI groups were observed only at the 3-month evaluation. The difficulty in using concentration when reporting GCF lysosomal enzyme activity is emphsized by comparison of the data from the DA group and the high and low enzyme activity subsets of the DI group.(ABSTRACT TRUNCATED AT 250 WORDS)

Lysosomal and cytoplasmic enzyme activity, crevicular fluid volume, and clinical parameters characterizing gingival sites with shallow to intermediate probing depths.

The biochemical analysis of gingival crevicular fluid (GCF) may offer a sensitive means of determining periodontal disease activity, including the transition of gingivitis to periodontitis. To continue our evaluation of the relationship between clinical and GCF parameters, 552 sites with shallow to intermediate (2.0-5.0 mm) probing depths (PD) were examined. The data were collected at baseline from 33 periodontitis patients participating in a longitudinal trial examining the relationship of changes in GCF biochemistry to attachment loss. Mesiobuccal sites were scored for dichotomous measures of bleeding on probing, gingival redness, suppuration, and plaque accumulation. In addition, GCF was collected using filter paper strips inserted into the sulcus for 30 seconds, eluted in buffer and assayed for activity of the enzymes beta-glucuronidase (BG), arylsulfatase (AS), and lactate dehydrogenase (LDH), markers for ground substance-degradation and cellular necrosis, respectively. Clinical and GCF parameters were evaluated by increasing PD. Plaque accumulation and bleeding on probing increased with increasing PD, although there was considerable overlap across groups. Suppuration was present in only a very small number of sites and the proportion of sites displaying gingival redness was not related to PD. GCF volume was grouped in 0.25-microliter increments, revealing a progressive shift with increasing PD toward a normal distribution around the median range of 0.51 to 0.75 microliter at 5.0 mm. Mean enzyme activities of BG, and to a lesser extent AS and LDH increased sharply from 2.0 to 3.0 mm, were relatively stable from 3.5 to 4.5 mm, and were significantly higher in 5.0 mm than 4.5 mm sites.(ABSTRACT TRUNCATED AT 250 WORDS)