Biology subjects

Kurniawan, N. A.

Publications and source records attributed to Kurniawan, N. A..

6 recordsLinked to original sources

bioRxiv2025

Substrate stiffness modulates phenotype-dependent fibroblast contractility and migration independent of TGF-β stimulation

During wound healing, fibroblasts undergo radical processes that impact their phenotype and behavior. They are activated, recruited to the injury site, assume a contractile phenotype, and secrete extracellular matrix proteins to orchestrate tissue repair. Thus, fibroblasts response require dynamic changes in cytoskeleton assembly and organization, adhesion morphology, and force generation. At the same time, fibroblasts experience changes in environmental stiffness during tissue wounding and healing. Although cells are generally known to use their adhesion-contraction machinery to sense microenvironmental stiffness, little is known about how stiffness affects the fibroblast phenotypical transition and behavior in wound healing. Here we demonstrate that stiffness plays a deterministic role in determining fibroblast phenotype, surprisingly even overruling the classical TGF-{beta}-mediated stimulation. By combining morphometric analysis, traction force microscopy, and single-cell migration analysis, we show that environmental stiffness primes the cytoskeletal and mechanical responses of fibroblasts, strongly modulating their morphology, force generation, and migration behavior. Our study, therefore, points to the importance of tissue stiffness as a key mechanobiological regulator of fibroblast behavior, thus serving as a potential target for controlling tissue repair.

biophysics↗

bioRxiv2021

Cardiac fibroblast mechanoresponse guides anisotropic organization of hiPSC-derived cardiomyocytes in vitro

The human myocardium is a mechanically active tissue typified by anisotropic organization of the resident cells (cardiomyocytes (CMs) and cardiac fibroblasts (cFBs)) and the extracellular matrix (ECM). Upon ischemic injury, the anisotropic tissue is replaced by disorganized scar tissue, eventually resulting in loss of coordinated contraction. Efforts to re-establish tissue anisotropy in the injured myocardium are hampered by a lack of understanding on how CM and/or cFB structural organization is affected by the two major physical cues inherent in the myocardium: ECM organization and cyclic mechanical strain. Herein, we investigate the singular and combined effect of ECM (dis)organization and cyclic strain in a 2D human in vitro co-culture model of the myocardial microenvironment. We show that (an)isotropic ECM protein patterning can guide the orientation of CMs and cFBs, both in mono- and co-culture. Subsequent application of uniaxial cyclic strain - mimicking the local anisotropic deformation of beating myocardium - causes no effect when applied parallel to the anisotropic ECM. However, when cultured on isotropic substrates, cFBs, but not CMs, orient away from the direction of cyclic uniaxial strain (strain avoidance). In contrast, CMs show strain avoidance via active remodeling of their sarcomeres only when co-cultured with at least 30% cFBs. Paracrine signaling or N-cadherin-mediated communication between CMs and cFBs were no contributing factors, but our findings suggest that the mechanoresponsive cFBs provide structural guidance for CM orientation and elongation. Our study therefore highlights a synergistic mechanobiological interplay between CMs and cFBs in shaping tissue organization, which is of relevance for regenerating functionally organized myocardium.

biophysics↗

bioRxiv2020

Computationally guided in-vitro vascular growth model reveals causal link between flow oscillations and disorganized neotissue

AO_SCPLOWBSTRACTC_SCPLOWDisturbed shear stress is thought to be the driving factor of neointimal hyperplasia in blood vessels and grafts, for example in hemodialysis conduits. Despite the common occurrence of neointimal hyperplasia, however, the mechanistic role of shear stress is unclear. This is especially problematic in the context of in situ scaffold-guided vascular regeneration, a process strongly driven by the scaffold mechanical environment. To address this issue, we herein introduce an integrated numerical-experimental approach to reconstruct the graft-host response and interrogate the mechanoregulation in dialysis grafts. Starting from patient data, we numerically analyze the biomechanics at the vein-graft anastomosis of a hemodialysis conduit. Using this biomechanical data, we show in an in vitro vascular growth model that oscillatory shear stress, in the presence of cyclic strain, favors neotissue development by reducing the secretion of remodeling markers by vascular cells and promoting the formation of a dense and disorganized collagen network. These findings identify scaffold-based shielding of cells from oscillatory shear stress as a potential handle to inhibit neointimal hyperplasia in grafts.

bioengineering↗

bioRxiv2020

Human cerebral tissues created via active cellular reaggregation produce functionally interconnected 3D neuronal network to mimic pathological circuit disturbance

Various characteristics of a developing central nervous system, including sensory input-output1,2, neuronal migration3,4, and regionalization3,5, have been recapitulated through recent advances in the culture of brain organoids. These organoids can model the fundamental processes in brain development and disease. A remaining critical challenge, however, is to achieve complex neuronal networks with functional interconnectivity as in native brain tissue. Generation of current organoid models originates from classic dissociation-reaggregation paradigms6, often relying on mechanically-enforced quick reaggregation of pluripotent stem cells7. Here we describe an alternative method that promotes matrix-supported active (migrative) reaggregation of cells (MARC), reminiscent of in vivo developmental morphing processes, to engineer multi-regional brain tissues in vitro. Measurements of neuronal activity in intact 3D tissues revealed functional interconnectivity, characteristic of cerebral neuronal networks. As a proof of concept, we show that interconnected cerebral tissues produced using this approach can mimic propagation of epileptiform discharges in a custom-built in-vitro platform.

bioengineering↗

bioRxiv2020

Molecular packing structure of fibrin fibers resolved by X-ray scattering and molecular modeling

Fibrin is the major extracellular component of blood clots and a proteinaceous hydrogel used as a versatile biomaterial. Fibrin forms branched networks of polymeric fibers, built of laterally associated double-stranded protofibrils. This multiscale hierarchical structure is crucial for the extraordinary mechanical resilience of blood clots. Yet, the structural basis of clot mechanical properties remains largely unclear due, in part, to the unresolved molecular packing structure of fibrin fibers. Here we quantitatively assess the packing structure of fibrin fibers by combining Small Angle X-ray Scattering (SAXS) measurements of fibrin networks reconstituted under a wide range of conditions with computational molecular modeling of fibrin oligomers. The number, positions, and intensities of the Bragg peaks observed in the SAXS experiments were reproduced computationally based on the all-atom molecular structure of reconstructed fibrin protofibrils. Specifically, the model correctly predicts the intensities of the reflections of the 22.5 nm axial repeat, corresponding to the half-staggered longitudinal arrangement of fibrin molecules. In addition, the SAXS measurements showed that protofibrils within fibrin fibers have a partially ordered lateral arrangement with a characteristic transverse repeat distance of 13 nm, irrespective of the fiber thickness. These findings provide fundamental insights into the molecular structure of fibrin clots that underlies their biological and physical properties.

biophysics↗

bioRxiv2019

Human in vitro model of material-driven vascular regeneration reveals how cyclic stretch and shear stress differentially modulate inflammation and tissue formation

1Resorbable synthetic scaffolds designed to regenerate living tissues and organs inside the body emerge as a clinically attractive technology to replace diseased blood vessels. However, mismatches between scaffold design and in vivo hemodynamic loading (i.e., cyclic stretch and shear stress) can result in aberrant inflammation and adverse tissue remodeling, leading to premature graft failure. Yet, the underlying mechanisms remain elusive. Here, a human in vitro model is presented that mimics the transient local inflammatory and biomechanical environments that drive scaffold-guided tissue regeneration. The model is based on the co-culture of human (myo)fibroblasts and macrophages in a bioreactor platform that decouples cyclic stretch and shear stress. Using a resorbable supramolecular elastomer as the scaffold material, it is revealed that cyclic stretch initially reduces pro-inflammatory cytokine secretion and, especially when combined with shear stress, stimulates IL-10 secretion. Moreover, cyclic stretch stimulates downstream (myo)fibroblast proliferation and neotissue formation. In turn, shear stress attenuates cyclic-stretch-induced tissue growth by enhancing MMP-1/TIMP-1-mediated collagen remodeling, and synergistically alters (myo)fibroblast phenotype when combined with cyclic stretch. The findings suggest that shear stress acts as a stabilizing factor in cyclic stretch-induced tissue formation and highlight the distinct roles of hemodynamic loads in the design of resorbable vascular grafts.

bioengineering↗