Novel method to produce a layered 3D scaffold for human pluripotent stem cell-derived neuronal cells

BACKGROUND

Three-dimensional (3D) in vitro models have been developed into more in vivo resembling structures. In particular, there is a need for human-based models for neuronal tissue engineering (TE). To produce such a model with organized microenvironment for cells in central nervous system (CNS), a 3D layered scaffold composed of hydrogel and cell guiding fibers has been proposed.

NEW METHOD

Here, we describe a novel method for producing a layered 3D scaffold consisting of electrospun poly (L,D-lactide) fibers embedded into collagen 1 hydrogel to achieve better resemblance of cells' natural microenvironment for human pluripotent stem cell (hPSC)-derived neurons. The scaffold was constructed via a single layer-by-layer process using an electrospinning technique with a unique collector design.

RESULTS

The method enabled the production of layered 3D cell-containing scaffold in a single process. HPSC-derived neurons were found in all layers of the scaffold and exhibited a typical neuronal phenotype. The guiding fiber layers supported the directed cell growth and extension of the neurites inside the scaffold without additional functionalization.

COMPARISON WITH EXISTING METHODS

Previous methods have required several process steps to construct 3D layer-by-layer scaffolds.

CONCLUSIONS

We introduced a method to produce layered 3D scaffolds to mimic the cell guiding cues in CNS by alternating the soft hydrogel matrix and fibrous guidance cues. The produced scaffold successfully enabled the long-term culture of hPSC-derived neuronal cells. This layered 3D scaffold is a useful model for in vitro and in vivo neuronal TE applications.

A role for telomere length and chromosomal damage in idiopathic pulmonary fibrosis

BACKGROUND

Idiopathic pulmonary fibrosis is a fatal lung disease characterized by a progressive formation of fibroblastic foci in the interstitium. This disease is strongly associated with telomere dysfunction but the extent of telomere shortening and consequent chromosomal damage within IPF lungs and with regional disease severity remains unknown.

METHODS

Explanted IPF lungs (n = 10) were collected from transplant surgeries with six samples per lung analysed to capture the regional heterogeneity ranging from mild to severe disease. Non-used donor lungs (n = 6) were collected as "healthy" controls. Structural changes related to disease severity (microCT surface density), relative telomere length (real-time qPCR), and quantitative histology of chromosomal damage (γ-H2A.X) and extracellular matrix (elastin, total collagen, collagen 1, and collagen 3) were measured. A multivariate linear mixed-effects model controlling for subject was used to identify association of disease severity or fibrotic markers with telomere length and chromosomal damage.

RESULTS

We observed shorter telomere length (p = 0.001) and increased chromosomal damage (p = 0.018) in IPF lungs compared to controls. In IPF lungs, telomere length was associated with total collagen (p < 0.001) but not with structural changes of disease severity. Chromosomal damage was positively associated with increased elastin (p = 0.006) and negatively with structural disease severity (p = 0.046). Extensive γ-H2A.X staining was also present in airway epithelial cells.

CONCLUSIONS

Telomere length and chromosomal damage are involved in IPF with regional variation in telomere length and chromosomal damage associated with pathological changes in tissue structure and the extracellular matrix.

APRi predicts native liver survival by reflecting portal fibrogenesis and hepatic neovascularization at the time of portoenterostomy in biliary atresia

BACKGROUND

Aspartate aminotransferase-to-platelet ratio index (APRi) may be useful noninvasive prognostic tool in biliary atresia (BA). We studied whether APRi predicts native liver survival and parallels biochemical and immunohistological signs of liver injury and fibrogenesis at the time of Kasai portoenterostomy (PE).

METHODS

Serum and liver specimens were obtained at PE from 29 BA patients for liver biochemistry including APRi, histology and immunohistochemical analysis of collagen 1, α-SMA and CD34. APRi values were related to native liver survival and other clinical data as well as serum liver biochemistry, liver histology and immunohistochemistry at PE.

RESULTS

Median age at PE was 63 (range 7-141) days and median APRi was 0.92 (0.13-6.39). APRi had strong positive correlations with patient age (r=0.684, p<0.001) and biochemical signs of hepatocyte injury and cholestasis. APRi showed no significant correlations with Metavir (r=0.336, p=0.223) or Ishak (r=0.289, p=0.262) global fibrosis scores nor with liver collagen 1 expression (r=0.260, p=0.222). In contrast, portal fibrosis score (r=0.515, p=0.013), predominantly portal α-SMA expression (r=0.519, p=0.015) and amount CD34-positive microvessels in the centrizonal region (r=0.604, p=0.004) correlated positively with APRi. Patients (n=10) who underwent liver transplantation had significantly higher APRi at presentation (1.34 vs. 0.77, p=0.017) compared to those who survived with native liver (n=19).

CONCLUSIONS

APRi correlates with portal fibrosis, expression of α-SMA and the amount of CD34-positive microvessels, suggesting that APRi predicts native liver survival by reflecting portal myofibroblastic cell activation, fibrogenesis and associated neovascularization.

Myofibroblastic cell activation and neovascularization predict native liver survival and development of esophageal varices in biliary atresia

AIM: To study the relation between collagen 1, α-smooth muscle actin (α-SMA) and CD34 expression and the most essential portoenterostomy (PE) outcomes.

METHODS: Liver specimens were obtained at PE from 33 biliary atresia (BA) patients for immunohistochemical analysis of collagen 1, α-SMA and CD34. Liver biopsies from 35 organ donors were used as controls. Expression patterns were related to clinical data including age at PE, serum total and conjugated bilirubin concentration at the time of PE and during follow-up, incidence of esophageal varices in follow-up upper gastrointestinal endoscopies, and native liver survival as well as to detailed histopathological findings.

RESULTS: Collagen 1 (16.4% vs 4.5%, P < 0.0001), α-SMA (17.9% vs 4.6%, P < 0.0001) and CD34 (4.9% vs 3.8%, P = 0.017) were markedly overexpressed in BA patients compared with controls. Patients who underwent liver transplantation by age of two years had significantly higher expression of collagen 1 (18.6% vs 13.7%, P = 0.024), α-SMA (20.4% vs 15.4%, P = 0.009) and CD34 (5.9% vs 4.0%, P = 0.029) at PE compared with native liver survivors. CD34-positive microvessels were identified in the centrizonal region close to central vein in every BA patient. In majority of BA cases (56%) neovascularization was frequent as CD34-positive microvessels were observed in over half of the hepatic lobules. In controls, the CD34-positive microvessels were rare as they were completely absent in 40 % and were found in less than 5 % of the hepatic lobules in the rest. The difference between BA patients and controls was significant (P < 0.0001). Patients who developed esophageal varices by two years had significantly higher expression of CD34 at PE compared with patients without varices (5.6% vs 4.0%, P = 0.019). Expression of α-SMA (r = 0.758, P < 0.0001) and collagen 1 (r = 0.474, P = 0.016), and the amount of CD34-positive microvessels (r = 0.356, P = 0.047) were related to patient age at PE.

CONCLUSION: Hepatic myofibroblastic cell activation, fibrogenesis and neovascularization are enhanced in BA, progress with increasing PE age and relate to native liver survival and development of esophageal varices.