The effect of polymer molecular weight and cell seeding density on viability of cells entrapped within PEGDA hydrogel microspheres

Abstract

Cell microencapsulation can be used in tissue engineering as a scaffold or physical barrier that provides immunoisolation for donor cells. When used as a barrier, microencapsulation shields donor cells from the host immune system when implanted for cell therapies. Maximizing therapeutic product delivery per volume of microencapsulated cells necessitates first optimising the viability of entrapped cells. Although cell microencapsulation within alginate is well described, best practices for cell microencapsulation within polyethylene glycol is still being elucidated. In this study we microencapsulate mouse preosteoblast cells within polyethylene glycol diacrylate (PEGDA) hydrogel microspheres of varying molecular weight or seeding densities to assess cell viability in relation to cell density and polymer molecular weight. Diffusion studies revealed molecule size permissible by each molecular weight PEGDA towards correlating viability with polymer mesh size. Results demonstrated higher cell viability in higher molecular weight PEGDA microspheres and when cells were seeded at higher cell densities.     

A miniature and mobile intermittent pneumatic compression device for the prevention of deep-vein thrombosis after joint replacement

The WizAir-DVT is a miniature, lightweight (690 g), battery-operated and mobile intermittent pneumatic compression device (ICD), which enables continuous intraoperative use and immediate patient mobilization postoperatively. We compared its efficacy with a commonly used ICD, the Kendall SCD. Peak femoral vein flow velocity was measured in 20 apparently healthy volunteers at rest and with each device: we found no significant differences between them. A second prospective, randomized, clinical trial was used to compare the efficiency of the device in preventing deep venous thrombosis (DVT) after joint replacement in 50 patients (n=25/group). None developed DVT. Doppler ultrasonography revealed no significant differences. The WizAir-DVT antithrombotic compression device is as safe and effective as the Kendall SCD.     

Retrospective analysis of clinical outcomes in bilateral cleft lip and palate patients after secondary alveolar bone grafting and premaxilla osteotomy,using a new dento-maxillary scoring system

Evaluation of relevant clinical outcomes in patients with bilateral cleft lip and palate (BCLP) after secondary aveolar bone grafting (SABG) and premaxilla osteotomy (PMO), through the use of a new scoring system.Data were collected retrospectively from all patients with BCLP who were operated on between 2004 and 2014, at the end of follow-up. The treatment protocol consisted of SABG + PMO in patients aged between 9 and 13 years. At the end of follow-up, the following parameters were scored: (un)interrupted dental arch, skeletal sagittal relationship, bone height using the Bergland/Abyholm criteria, and the presence of postoperative fistula. These parameters were combined to produce a dento-maxillary scoring system, giving a final score between 1 and 10. For statistical analysis, the independent t-test was used.Of 55 children, 45 were suitable for analysis. The mean age at time of surgery was 12.0 years (8.9–16.4 yrs), and the mean follow-up time was 11.7 years (5.8–15.8 yrs). The average number of surgeries executed under general anesthesia was 6 (range: 3–11). The average dento-maxillary score in this patient cohort was 7.6 (1–10; median: 8). Among these patients, 31 had an uninterrupted dental arch; the average Bergland/Abyholm score was 2.07; 30 patients exhibited an Angle class I incisor relationship; and, in 38 cases, the oronasal communication was closed after SABG + PMO treatment. A significant effect of fistulas was seen on dento-maxillary score (p = 0.001). Specifically, a significant effect of fistulas was seen on interrupted dental arch (p = 0.002) and on Bergland/Abyholm score (p = 0.037).The proposed dento-maxillary scoring system is a straightforward tool that can be used to describe and analyze the amount of dento-maxillary rehabilitation at the end of the treatment. Persistence of oronasal fistulas in patients with BCLP has a significant impact on interruption of the dental arch, and can influence dental results at the end of the second decade.     

Doppler‐guided haemorrhoidal artery ligation in patients with Crohn’s disease

Aim: The outcome of Doppler‐guided haemorrhoidal artery ligation (DGHAL) was assessed in patients with Crohn’s disease (CD) suffering from grade III haemorrhoids. Method: A retrospective study was carried out of patients with CD and symptomatic Grade III haemorrhoids treated by DGHAL. Perioperative and follow‐up data were retrieved from our database of patients undergoing DGHAL. Results: The study included seven men and six women. The mean age was 34 years old. All had CD without anorectal involvement. The median duration of haemorrhoidal symptoms was 6.3 years. There was no mortality, new incontinence, faecal impaction, urinary retention, abscess formation or persistent pain following the procedure. Mean pain score based on a visual analogue scale (VAS) decreased from 2.4 at 24 h postoperatively to 1.6 on the seventh postoperative day. All patients had completely recovered by the third postoperative day. At 18 months, three (77%) of the patients were asymptomatic and three had recurrent symptoms. Conclusion: Doppler‐guided haemorrhoidal artery ligation is safe and effective in treating Grade III haemorrhoids in patients with CD without rectal involvement.