Athanasios Tyraskis

Preservation of micro-architecture and angiogenic potential in a pulmonary acellular matrix obtained using intermittent intra-tracheal flow of detergent enzymatic treatment

Tissue engineering of autologous lung tissue aims to become a therapeutic alternative to transplantation. Efforts published so far in creating scaffolds have used harsh decellularization techniques that damage the extracellular matrix (ECM), deplete its components and take up to 5 weeks to perform. The aim of this study was to create a lung natural acellular scaffold using a method that will reduce the time of production and better preserve scaffold architecture and ECM components. Decellularization of rat lungs via the intratracheal route removed most of the nuclear material when compared to the other entry points. An intermittent inflation approach that mimics lung respiration yielded an acellular scaffold in a shorter time with an improved preservation of pulmonary micro-architecture. Electron microscopy demonstrated the maintenance of an intact alveolar network, with no evidence of collapse or tearing. Pulsatile dye injection via the vasculature indicated an intact capillary network in the scaffold. Morphometry analysis demonstrated a significant increase in alveolar fractional volume, with alveolar size analysis confirming that alveolar dimensions were maintained. Biomechanical testing of the scaffolds indicated an increase in resistance and elastance when compared to fresh lungs. Staining and quantification for ECM components showed a presence of collagen, elastin, GAG and laminin. The intratracheal intermittent decellularization methodology could be translated to sheep lungs, demonstrating a preservation of ECM components, alveolar and vascular architecture. Decellularization treatment and methodology preserves lung architecture and ECM whilst reducing the production time to 3 h. Cell seeding and in vivo experiments are necessary to proceed towards clinical translation.

Decellularised skeletal muscles allow functional muscle regeneration by promoting host cell migration

Pathological conditions affecting skeletal muscle function may lead to irreversible volumetric muscle loss (VML). Therapeutic approaches involving acellular matrices represent an emerging and promising strategy to promote regeneration of skeletal muscle following injury. Here we investigated the ability of three different decellularised skeletal muscle scaffolds to support muscle regeneration in a xenogeneic immune-competent model of VML, in which the EDL muscle was surgically resected. All implanted acellular matrices, used to replace the resected muscles, were able to generate functional artificial muscles by promoting host myogenic cell migration and differentiation, as well as nervous fibres, vascular networks, and satellite cell (SC) homing. However, acellular tissue mainly composed of extracellular matrix (ECM) allowed better myofibre three-dimensional (3D) organization and the restoration of SC pool, when compared to scaffolds which also preserved muscular cytoskeletal structures. Finally, we showed that fibroblasts are indispensable to promote efficient migration and myogenesis by muscle stem cells across the scaffolds in vitro. This data strongly support the use of xenogeneic acellular muscles as device to treat VML conditions in absence of donor cell implementation, as well as in vitro model for studying cell interplay during myogenesis.

A systematic review and meta‐analysis on fetal ovarian cysts: impact of size, appearance and prenatal aspiration

The objective of the study is to compare outcomes of ultrasound‐guided aspiration of fetal ovarian cysts with conservative management.

Histopathology of livers in patients with congenital portosystemic shunts (Abernethy malformation): a case series of 22 patients

Congenital portosystemic shunt (CPSS) is a congenital anomaly resulting in partial or complete diversion of the portal blood into the systemic circulation. The literature on the histological changes in livers of patients with CPSS is limited. Liver histology of 22 consecutive patients managed in our institution between 2001 and 2016 was reviewed. Twenty-one patients were children at the time of diagnosis. Thirty-two specimens were available and consisted of three explant livers and 29 biopsy samples from 19 patients. Sixteen samples were from wedge biopsies taken at the time of shunt closure. Thirteen were from core needle biopsies taken during clinical work-up. A variable proportion of portal tracts contained prominent thin-walled channels (PTWCs) and arterio-biliary dyads. The proportion of portal tracts containing triads, arterio-biliary dyads and biliary monads varied considerably in the different samples. Dilated inlet venules, increase in the number of portal arteries or the presence of portal arteries of increased size, deposition of copper-associated protein, sinusoidal dilatation, capillarization and intralobular individual arteries were present. Physiological nuclear vacuolation of periportal hepatocytes was absent in most samples from our paediatric patients. Presence of PTWCs, arterial-biliary dyads, increased arterial profiles in portal tracts and lobule and lack of the physiological periportal vacuolated hepatocytes in children are the most characteristic histological changes of CPSS in the liver periphery.

A retrospective multicenter study of the natural history of fetal ovarian cysts

AIM We investigated the natural history of fetal ovarian cysts to estimate the risk of torsion according to size. METHODS Cases were identified from 1/1/2000 until 1/1/2015. Data were collected pre- and postnatally on cyst size and sonographic features until an outcome of surgery, torsion, or resolution. Fishers exact test for categorical data and logistic regression for continuous data were used to test the significance of size on torsion; P value <0.05 was considered significant. RESULTS 37 patients with unilateral ovarian cysts were included. 12 (32%) resolved spontaneously prenatally, 14 (38%) resolved spontaneously postnatally, 5 (14%) underwent surgery postnatally and 6 (16%) cases underwent torsion. Rate of torsion increased with size from 0% (n=0) in cysts ≤20mm to 33% (n=2) in cysts >50mm; however, the overall trend failed to reach statistical significance (P=0.1). Cysts of 0-40mm had a significantly higher rate of spontaneous resolution (90% vs. 44% in >40mm, P=0.003), but the rate of torsion was not significantly different (10% in 0-40mm vs. 25% in >40mm, P=0.26). The median time to postnatal resolution was 10 (5-27) weeks in those treated conservatively. CONCLUSION Cysts >40mm are significantly less likely to resolve spontaneously; however torsion showed no significant correlation with cyst size. No complications were observed in cysts <20mm. LEVEL OF EVIDENCE IV, case series with no comparison group.