Location matters: Offset in tissue-engineered vascular graft implantation location affects wall shear stress in porcine models

Objective

Although surgical simulation using computational fluid dynamics has advanced, little is known about the accuracy of cardiac surgical procedures after patient-specific design. We evaluated the effects of discrepancies in location for patient-specific simulation and actual implantation on hemodynamic performance of patient-specific tissue-engineered vascular grafts (TEVGs) in porcine models.

Methods

Magnetic resonance angiography and 4-dimensional (4D) flow data were acquired in porcine models (n = 11) to create individualized TEVGs. Graft shapes were optimized and manufactured by electrospinning bioresorbable material onto a metal mandrel. TEVGs were implanted 1 or 3 months postimaging, and postoperative magnetic resonance angiography and 4D flow data were obtained and segmented. Displacement between intended and observed TEVG position was determined through center of mass analysis. Hemodynamic data were obtained from 4D flow analysis. Displacement and hemodynamic data were compared using linear regression.

Results

Patient-specific TEVGs were displaced between 1 and 8 mm during implantation compared with their surgically simulated, intended locations. Greater offset between intended and observed position correlated with greater wall shear stress (WSS) in postoperative vasculature (P < .01). Grafts that were implanted closer to their intended locations showed decreased WSS.

Conclusions

Patient-specific TEVGs are designed for precise locations to help optimize hemodynamic performance. However, if TEVGs were implanted far from their intended location, worse WSS was observed. This underscores the importance of not only patient-specific design but also precision-guided implantation to optimize hemodynamics in cardiac surgery and increase reproducibility of surgical simulation.

Role of ductular reaction and ductular-canalicular junctions in identifying severe primary biliary cholangitis

Background & Aims

Primary biliary cholangitis (PBC) is a chronic cholangiopathy characterised by immuno-mediated injury of interlobular bile ducts leading to intrahepatic cholestasis and progressive liver fibrosis. PBC histology is characterised by portal inflammation, progressive fibrosis, ductopenia, and the appearance of the so-called ductular reaction. The aim of the present study was to investigate the pathogenetic relevance of ductular reaction in PBC.

Methods

Liver biopsies were collected from naïve people with PBC (N = 87). Clinical-serological parameters were obtained at diagnosis and after 1 year of ursodeoxycholic acid (UDCA) treatment. Histological staging was performed on all slides according to multiple scoring systems and criteria for PBC. Liver samples were obtained from Mdr2 ^-/- mice treated with or without UDCA. Samples were processed for histology, immunohistochemistry, and immunofluorescence.

Results

Ductular reaction in people with PBC correlated with the disease stage and liver fibrosis, but not with disease activity; an extensive ductular reaction correlated with serum alkaline phosphatase levels at diagnosis, response to UDCA, and individuals' estimated survival, independently from other histological parameters, including disease stage. In people with PBC, reactive ductules were associated with the establishment of junctions with bile canaliculi and with fibrogenetic cell activation. Consistently, in a mouse model of intrahepatic cholestasis, UDCA treatment was effective in reducing ductular reaction and fibrosis and increasing ductular-canalicular junctions.

Conclusions

Extensive ductular reaction outlines a severe histologic phenotype in PBC and is associated with an inadequate therapy response and a worse estimated prognosis.

Lay summary

In people affected by primary biliary cholangitis (PBC), the histological appearance of extensive ductular reaction identifies individuals at risk of progressive fibrosis. Ductular reaction at diagnosis correlates with the lack of response to first-line therapy with ursodeoxycholic acid and serves to restore ductular-canalicular junctions in people with PBC. Assessing ductular reaction extension at diagnosis may add valuable information for clinicians.

Secreted matrix metalloproteinase-14 is a predictor for antifibrotic effect of IC-2-engineered mesenchymal stem cell sheets on liver fibrosis in mice

Introduction

Transplantation of IC-2-engineered bone marrow-derived mesenchymal stem cell (BM-MSC) sheets (IC-2 sheets) was previously reported to potentially reduce liver fibrosis.

Methods

This study prepared IC-2-engineered cell sheets from multiple lots of BM-MSCs and examined the therapeutic effects of these cell sheets on liver fibrosis induced by carbon tetrachloride in mice. The predictive factors for antifibrotic effect on liver fibrosis were tried to identify in advance.

Results

Secreted matrix metalloproteinase (MMP)-14 was found to be a useful predictive factor to reduce liver fibrosis. Moreover, the cutoff index of MMP-14 for 30% reduction of liver fibrosis was 0.918 fg/cell, judging from univariate analysis and receiver operating curve analysis. In addition, MMP-13 activity and thioredoxin contents in IC-2 sheets were also inversely correlated with hepatic hydroxyproline contents. Finally, IC-2 was also found to promote MMP-14 secretion from BM-MSCs of elderly patients. Surprisingly, the values of secreted MMP-14 from BM-MSCs of elderly patients were much higher than those of young persons.

Conclusion

The results of this study suggest that the IC-2 sheets would be applicable to clinical use in autologous transplantation for patients with cirrhosis regardless of the patient's age.

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IC-2- sheets from multiple lots of BM-MSCs ameliorate liver fibrosis in mice.

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Secreted MMP-14 is a useful predictive marker to reduce liver fibrosis.

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MMP-13 and thioredoxin in IC-2 sheets were also associated with liver fibrosis.

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IC-2 also promotes MMP-14 secretion from BM-MSCs of elderly patients.

Distinct contributions of meprins to skin regeneration after injury - Meprin α a physiological processer of pro-collagen VII

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Meprins subtly support epidermal and dermal skin wound healing.

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Loss of both meprins reduces re-epithelialization and wound macrophage abundance.

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Meprin α is a physiological maturing proteinase of collagen VII.

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Meprins are reduced in recessive dystrophic epidermolysis bullosa skin.

Astacin-like proteinases (ALPs) are regulators of tissue and extracellular matrix (ECM) homeostasis. They convey this property through their ability to convert ECM protein pro-forms to functional mature proteins and by regulating the bioavailability of growth factors that stimulate ECM synthesis. The most studied ALPs in this context are the BMP-1/tolloid-like proteinases. The other subclass of ALPs in vertebrates – the meprins, comprised of meprin α and meprin β – are emerging as regulators of tissue and ECM homeostasis but have so far been only limitedly investigated. Here, we functionally assessed the roles of meprins in skin wound healing using mice genetically deficient in one or both meprins. Meprin deficiency did not change the course of macroscopic wound closure. However, subtle but distinct contributions of meprins to the healing process and dermal homeostasis were observed. Loss of both meprins delayed re-epithelialization and reduced macrophage infiltration. Abnormal dermal healing and ECM regeneration was observed in meprin deficient wounds. Our analyses also revealed meprin α as one proteinase responsible for maturation of pro-collagen VII to anchoring fibril-forming-competent collagen VII in vivo. Collectively, our study identifies meprins as subtle players in skin wound healing.

A Role for Polo-Like Kinase 4 in Vascular Fibroblast Cell-Type Transition

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PLK4, previously known as a centriole-associated factor, regulates the transcription factor activity of serum response factor.

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PLK4 inhibition blocks the profibrogenic cell state transition of vascular fibroblasts.

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PLK4’s activation and gene expression are regulated by PDGF receptor and epigenetic reader BRD4, respectively.

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Periadventitial administration of a PLK4 inhibitor mitigates vascular fibrosis.

Polo-like kinase 4 (PLK4) is canonically known for its cytoplasmic function in centriole duplication. Here we show a noncanonical PLK4 function of regulating the transcription factor SRF’s nuclear activity and associated myofibroblast-like cell-type transition. In this context, we have further found that PLK4’s phosphorylation and transcription are respectively regulated by PDGF receptor and epigenetic factor BRD4. Furthermore, in vivo experiments suggest PLK4 inhibition as a potential approach to mitigating vascular fibrosis.

Endoscopic repair of the urinary bladder with magnetically labeled mesenchymal stem cells: Preliminary report

Introduction

Transurethral resection of a bladder tumor (TURBT) using a resectoscope has been standard treatment for bladder cancer. However, no treatment method promotes the repair of resected bladder tissue. The aim of this study was to examine the healing process of damaged bladder tissue after a transurethral injection of bone marrow mesenchymal stem cells (MSCs) into the bladder. An injection of magnetic MSCs meant that they accumulated in the damaged area of the bladder. Another aim of this study was to compare the acceleration effect of MSC magnetic delivery on the repair of bladder tissue with that of non-magnetic MSC injection.

Methods

Using the transurethral approach to avoid opening the abdomen, electrofulguration was carried out on the anterior wall of the urinary bladder of white Japanese rabbits to mimic tumor resection. An external magnetic field directed at the injured site was then applied using a 1-tesla (T) permanent magnet. Twelve rabbits were divided into three groups. The 1 × 10⁶ of magnetically labeled MSCs were injected into the urinary bladder with or without the magnetic field (MSC M+ and MSC M-groups, respectively), and phosphate-buffered saline was injected as the control. The effects of the injections in the three groups at 14 days were examined using 4.7-T magnetic resonance imaging (MRI) then macroscopically and histologically. The mRNA expressions of several cytokines in the repair tissues were assessed using real-time polymerase chain reaction.

Results

The macroscopic findings showed the area of repair tissue in the MSC M+ group to be larger than that in either the MSC M-group or control group. MRI clearly depicted the macroscopic findings. The histological study showed that repair of the cauterized area with myofibrous tissue was significantly better in the MSC M+ group than that in either the MSC M-group or control group, although there was no significant difference in several mRNA cytokines among the three groups at 14 days after surgery.

Conclusions

The magnetic delivery of MSCs shows promise as an effective, minimally invasive method of enhancing tissue regeneration after TURBT.

Cells from the skin of patients with systemic sclerosis secrete chitinase 3-like protein 1

Background

The chitinase-like protein, Chi3L1, is associated with increased fibrotic activity as well as inflammatory processes. The capacity of skin cells from systemic sclerosis (SSc) patients to produce Chi3L1, and the stimulation of its synthesis by cytokines or growth factors known to be associated with SSc, was investigated.

Methods

Cells were isolated from forearm and/or abdomen skin biopsies taken from SSc patients and normal individuals and stimulated with cytokines and growth factors to assess Chi3L1 expression. Chi3L1-expressing cells were characterized by immunohistochemical staining.

Results

Chi3L1 was not secreted by skin cells from normal individuals nor was its synthesis induced by any of the cytokines or growth factors investigated. In contrast, Chi3L1 secretion was induced by OSM or IL-1 in cells from all forearm biopsies of SSc patients, and endogenous secretion in the absence of cytokines was detected in several specimens. Patients with Chi3L1-producing cells at both the arm and abdomen had a disease duration of less than 3 years. Endogenous Chi3L1 production was not a property of the major fibroblast population nor of myofibroblasts, but rather was related to the presence of stem-like cells not present in normal skin. Other cells, however, contributed to the upregulation of Chi3L1 by OSM.

Conclusions

The emergence of cells primed to respond to OSM with increased Chi3L1 production appears to be associated with pathological processes active in SSc.

General significance

The presence of progenitor cells expressing the chilectin Chi3L1 in SSc skin appears to play a role in the initiation of the disease process.

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Cells isolated from the skin of scleroderma patients secrete Chi3L1.

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Chi3L1 production is stimulated by oncostatin M or interleukin 1.

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Patients with Chi3L1 producing cells have disease duration of < 3 years.

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Chi3L1 production is a property of stem-like cells not present in normal skin.

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Other cells contribute to Chi3L1 upregulation by oncostatin M.

Reversible conversion of epithelial and mesenchymal phenotypes in SV40 large T antigen-immortalized rat liver cell lines

EMT (epithelial–mesenchymal transition) is a key process in the development of liver fibrosis. This process is also essential for liver morphogenesis in embryonic development. To study the cellular and molecular basis of EMT, we established two phenotypically different SV40 large T antigen-immortalized cell lines from rat hepatocytes. The first cell line, which had an epithelial morphology and was established in DMEM (Dulbecco’s modified Eagle’s medium)/Ham’s F-12 (DF)-based medium (RL/DF cells), expressed CK18 (cytokeratin 18), a marker of parenchymal hepatocytes. The other, a mesenchymal-like cell line established in DMEM-based medium (RL/DMEM cells), expressed αSMA (α-smooth muscle actin), a marker of hepatic myofibroblasts. Epithelial RL/DF cells underwent phenotypic changes, such as increased expression of αSMA, when the culture medium was switched to DMEM-based medium. In contrast, mesenchymal RL/DMEM cells were induced to express the epithelial marker CK18 with a concomitant decrease in αSMA expression when the culture medium was replaced with DF-based medium. These cell lines may provide novel in vitro models for the study of the conversion between epithelial and mesenchymal phenotypes during EMT in liver fibrosis and morphogenesis.