Tissue-to-Cellular Deformation Coupling in Cell-Microintegrated Elastomeric Scaffolds

Monokine stimulation of interleukin-11 production by human vascular smooth muscle cells in vitro

Elevation of free fatty acids (FFAs) is known to affect microvascular function and contribute to obesity-associated insulin resistance, hypertension, and microangiopathy. Proliferative and synthetic vascular smooth muscle cells (VSMCs) increase intimal thickness and destabilize atheromatous plaques. This study aimed to investigate whether saturated palmitic acid (PA) and monounsaturated oleic acid (OA) modulate autophagy activity, cell proliferation, and vascular tissue remodeling in an aortic VSMC cell line. Exposure to PA and OA suppressed growth of VSMCs without apoptotic induction, but enhanced autophagy flux with elevation of Beclin-1, Atg5, and LC3I/II. Cotreatment with autophagy inhibitors potentiated the FFA-suppressed VSMC growth and showed differential actions of PA and OA in autophagy flux retardation. Both FFAs upregulated lectin-like oxidized low-density lipoprotein receptor 1 (LOX-1) but only OA increased LDL uptake by VSMCs. Mechanistically, FFAs induced hyperphosphorylation of Akt, ERK1/2, JNK1/2, and p38 MAPK. All pathways, except OA-activated PI3K/Akt cascade, were involved in the LOX-1 upregulation, whereas blockade of PI3K/Akt and MEK/ERK cascades ameliorated the FFA-induced growth suppression on VSMCs. Moreover, both FFAs exhibited tissue remodeling effect through increasing MMP-2 and MMP-9 expression and their gelatinolytic activities, whereas high-dose OA significantly suppressed collagen type I expression. Conversely, siRNA-mediated LOX-1 knockdown significantly attenuated the OA-induced tissue remodeling effects in VSMCs. In conclusion, OA and PA enhance autophagy flux, suppress aortic VSMC proliferation, and exhibit vascular remodeling effect, thereby leading to the loss of VSMCs and interstitial ECM in vascular walls and eventually the instability of atheromatous plaques. J. Cell. Biochem. 118: 1249-1261, 2017. © 2016 Wiley Periodicals, Inc.

Microarray analysis of senescent vascular smooth muscle cells: A link to atherosclerosis and vascular calcification

Matrix metalloproteinases (MMPs) are associated with tissue remodelling and repair. In non-vascular tissues, NR4A receptors have been involved in the regulation of MMPs by transcriptional repression mechanisms. Here, we analyse alternative mechanisms involving NR4A receptors in the modulation of MMP activity in vascular smooth muscle cells (VSMC). Lentiviral overexpression of NR4A receptors (NOR-1, Nurr1 and Nur77) in human VSMC strongly decreased MMP-2 and MMP-9 activities (analysed by zymography and DQ-gelatin assays) and protein levels. NR4A receptors also down-regulated MMP-2 mRNA levels. Real-time PCR analysis evidenced that alpha-2-macroglobulin (A2M), but not other MMP inhibitors (TIMP-1 and TIMP-2) were up-regulated in NR4A-transduced cells. Interestingly, A2M was expressed in human vascular tissues including the smooth muscle media layer. While NR4A receptors increased A2M expression and secretion in VSMC, NR4A knockdown significantly reduced basal A2M expression in these cells. The direct transcriptional regulation of the human A2M promoter by NR4A receptors was characterised in luciferase reporter assays, electrophoretic mobility shift assays and by chromatin immunoprecipitation, identifying a NGFI-B response element (NBRE-71/-64) essential for the NR4A-mediated induction. The blockade of A2M partially prevented the reduction of MMPs activity observed in NR4A-transduced cells. Although mouse A2M promoter was unresponsive to NR4A receptors, vascular MMP expression was attenuated in transgenic mice over-expressing human NOR-1 in VSMC challenged with lipopolysaccharide. Our results show that the pan-proteinase inhibitor A2M is expressed in the vasculature and that NR4A receptors modulate VSMC MMP activity by several mechanisms including the up-regulation of A2M.

Idiopathic Pulmonary Fibrosis (IPF) is a chronic, progressive, and often fatal form of interstitial lung disease. It is characterized by injury with loss of lung epithelial cells and abnormal tissue repair, resulting in replacement of normal functional tissue, abnormal accumulation of fibroblasts and myofibroblasts, deposition of extracellular matrix, and distortion of lung architecture which results in respiratory failure. Despite improvements in the diagnostic approach to IPF and active research in recent years, the molecular mechanisms of the disease remain poorly understood. This highly lethal lung disorder continues to pose major clinical challenges since an effective therapeutic regimen has yet to be identified and developed. For example, a treatment modality has been based on the assumption that IPF is a chronic inflammatory disease, yet most available anti-inflammatory drugs are not effective in treating it. Hence researchers are now focusing on understanding alternative underlying mechanisms involved in the pathogenesis of IPF in the hope of discovering potentially new pharmaceutical targets. This paper will focus on lung tissue repair, regeneration, remodeling, and cell types that may be important to consider in therapeutic interventions and includes a more detailed discussion of the potential targets of current therapeutic attack in pulmonary fibrosis. The discovery that adult bone marrow stem cells can contribute to the formation of differentiated cell types in other tissues, especially after injury, implies that they have the potential to participate in tissue remodeling, and perhaps regeneration. The current promise of the use of adult stem cells for tissue regeneration, and the belief that once irreversibly damaged tissue could be restored to a normal functional capacity using stem cell-based therapy, suggests a novel approach for treatment of diverse chronic diseases. However this optimism is tempered by current evidence that the pathogenesis of pulmonary fibrosis may involve the recruitment of bone marrow-derived fibroblasts, which are the key contributors to the pathogenesis of this chronic progressive disorder. Nevertheless, stem cell-related therapies are widely viewed as promising treatment options for patients suffering from various types of pulmonary diseases. Gender mismatched bone marrow or lung transplant recipients serve as natural populations in which to study the role of bone marrow-derived stem cells in recovery from pulmonary diseases. Understanding the mechanism of recruitment of stem cells to sites of injury, and their involvement in tissue repair, regeneration, and remodeling may offer a novel therapeutic target for developing more effective treatments against this fatal disorder. This article reviews the new concepts in the pathogenesis, current and future treatment options of pulmonary fibrosis, and the recent advances regarding the roles of stem cells in lung tissue repair, regeneration, and remodeling.

The proliferation and migration of vascular smooth muscle cells (VSMCs) are major cellular events in hypertension-induced vascular remodeling, which is closely involved in the progression of atherosclerosis (AS). Although long non-coding RNAs (lncRNAs) are gaining recognition as novel regulators of VSMCs, their functioning and role in AS remain to be elucidated. In the present study, the role of lncRNA ENST00000430945 (lncRNA 430945) in AS was investigated. VSMCs transfected with a small interfering RNA (siRNA; si-430945) and a negative control (si-NC) were used. Cell Counting Kit-8, wound-healing and Transwell migration arrays were performed to determine whether lncRNA 430945 influenced VSMC proliferation and migration. Furthermore, the study examined whether a correlation exists between lncRNA 430945 and the receptor tyrosine kinase-like orphan receptor 2 (ROR2) signaling pathway. It was found that the expression of lncRNA 430945 was high in human AS tissues, which in turn promoted angiotensin II (AngII)-induced VSMC proliferation. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blot analyses showed that lncRNA 430945 mediated the AngII-induced upregulation of ROR2. In addition, the microarray and RT-qPCR results showed that the expression of lncRNA 430945 was increased considerably in AS tissues. The downregulation of lncRNA 430945 significantly suppressed AngII-induced VSMC proliferation and migration. In addition, ROR2 levels in VSMCs transfected with si-430945 were markedly lower than those cells transfected with si-NC. Additionally, western blotting showed that lncRNA 430945 activated the signaling pathways associated with ROR2 and Ras homolog gene family member A (RhoA). The upregulation of lncRNA 430945 in AS promoted the proliferation and migration of VSMCs via activation of the ROR2/RhoA signaling pathway. Therefore, targeting ROR2 or RhoA may be a promising technique in developing therapeutic strategies for treating AS.

Tissue engineering and regenerative medicine have furnished a vast range of modalities to treat either damaged tissue or loss of soft tissue or its function. In most approaches, a temporary porous scaffold is required to support tissue regeneration. The scaffold should be designed such that the turnover synchronizes with tissue remodeling and regeneration at the implant site. Segmented polyester urethanes (PUs) used in this study were based on epsilon-caprolactone (CL) and co-monomers D,L-lactide (D,L-L) and gamma-butyrolactone (BL), and 1,4-butanediisocyanate (BDI). In vitro, the PUs were nontoxic and haemocompatible. To test in vivo biocompatibility, the PUs were further processed into porous structures and subcutaneously implanted in rats for a period up to 21 days. Tissue remodeling and scaffold turnover was associated with a mild tissue response. The tissue response was characterized by extensive vascularization through the interconnected pores, with low numbers of macrophages on the edges and stroma formation inside the pores of the implants. The tissue ingrowth appeared to be related to the extent of microphase separation of the PUs and foam morphology. By day 21, all of the PU implants were highly vascularized, confirming the pores were interconnected. Degradation of P(CL/D,L-L)-PU was observed at this time, whereas the other two PU types remained intact. The robust method reported here of manufacturing and processing, good mechanical properties, and in vivo tissue response of the porous P(CL/D,L-L)-PU and PBCL-PU makes them excellent candidates as biomaterials with an application for soft tissue remodeling, for example, for cardiovascular regeneration.

Introduction: Wnt-Inducible Secreted Protein-1 (WISP-1) and Placental Growth Factor (PlGF) were found to be induced within 72 hours in organ-cultured human saphenous vein. While both are members of the PDGF superfamily, WISP-1 is closely related to Connective Tissue Growth Factor and PlGF is closely related to VEGF. During vascular wound repair, WISP-1 may recruit vascular smooth muscle cells (VSMCs) and PlGF may recruit endothelial cells because of their respective similarities to previously characterized growth factors. We hypothesized that WISP-1 may be more effective at inducing migration of human VSMCs than PlGF. Methods: Lyophilized recombinant proteins (R&D Systems, Minneapolis, MN) were reconstituted in RPMI1640. Passage 4 VSMCs, all derived from a single saphenous vein for a single experiment, were used at 10,000 cells/well in 48-well chemotaxis chambers (Neuroprobe, Gaithersburg, MD). Each experiment was repeated 4 times using cells from a different saphenous vein for each experiment. Results: Both WISP-1 and PlGF induced a chemotactic response from the VSMCs. WISP-1 was maximally chemotactic at 1 ng/mL (approximately 0.026 nM) while the PlGF maximum was 10 ng/mL (approximately 0.36 nM). Further studies will define their differential chemotactic effect on endothelial cells. Conclusions: WISP-1 was 13.8 times more effective, on a molar basis, than PlGF at inducing VSMC chemotaxis. While both growth factors probably play a role in vascular wound repair, their performance in chemotaxis assays of VSMCs suggests that WISP-1 activity is directed toward VSMCs.

NR4A receptors up-regulate the antiproteinase alpha-2 macroglobulin (A2M) in vascular smooth muscle cells and modulate matrix metalloproteinase (MMP) activity

In a mouse model of menstruation stromal cells respond to breakdown of the tissue by changing their identity to become epithelial cells that are incorporated into the luminal epithelium which is rapidly 'healed' without scarring.

Growth and remodeling of soft tissues is a dynamic process and several theoretical frameworks have been developed to analyze the time-dependent, mechanobiological and/or biomechanical responses of these tissues to changes in external loads. Importantly, general processes can often be conveniently separated into truly non-steady contributions and steady-state ones. Depending on characteristic times over which the external loads are applied, time-dependent models can sometimes be specialized to respective time-independent formulations that simplify the mathematical treatment without compromising the goodness of the particularized solutions. Very few studies have analyzed the long-term, steady-state responses of soft tissue growth and remodeling following a direct approach. Here, we derive a mechanobiologically equilibrated formulation that arises from a general constrained mixture model. We see that integral-type evolution equations that characterize these general models can be written in terms of an equivalent set of time-independent, nonlinear algebraic equations that can be solved efficiently to yield long-term outcomes of growth and remodeling processes in response to sustained external stimuli. We discuss the mathematical conditions, in terms of orders of magnitude, that yield the particularized equations and illustrate results numerically for general arterial mechano-adaptations.

Interstitial growth and remodeling of biological tissues: Tissue composition as state variables

Surface remodeling of biological tissues through tissue growth or dissolution is deemed critical to their proper functioning, and is influenced by the deformation of the tissues during physiological activities. The present work attempts to develop a constitutive framework for deformation modulated surface remodeling of biological tissues. The framework is developed assuming finite deformation of the tissue, and the effect of deformation on the driving force for surface remodeling is determined from thermodynamic principles. The microscopic trends are upscaled to yield the remodeling-induced change in a macroscopic porous tissue. By way of application, the effect of deformation on the remodeling kinetics is determined for an incompressible elastic tissue. Depending on the ratio of the specific elastic stiffness and the specific Gibbs energy variation induced by the cell, the effect of deformation on the remodeling kinetics can be significant. It is found that both tensile and compressive deformation aid tissue dissolution (and dissuade growth). However, the magnitude of the effect is found to be different under tensile and compressive loadings, and critically depends on the reference frame used for the strain measurements. For Lagrangian strain measures (e.g., stretch, engineering strain), the increase in the dissolution kinetics per unit strain is higher under compressive loadings. On the other hand, for Eulerian strain measures (e.g., logarithmic or true strain), the effect of tensile loading on the dissolution kinetics is higher. This reinforces the need for proper reference frame definition for experimental strain measurements.

The growth and remodeling of a tissue depends on certain features in the history of its mechanical environment as well as its genetic makeup. The mechanical environment influences the tissue's developing morphology, the process of simply increasing the size of existing morphological structures, and the formation of the proteins of which the tissue is constructed. The relationships between genetic information, various epigenetic mechanisms and tissue development are discussed. The developmental growth and remodeling of most structural tissues are enhanced by the use of those tissues and retarded by their disuse. The mechanical or mathematical modeling of tissue growth and development using cellular automata models and continuum mechanical models is reviewed.

Inhibition of intimal hyperplasia in murine aortic allografts by the oral administration of the transforming growth factor-beta receptor I kinase inhibitor SD-208