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Biology subjects

Dhand, A. P.

Publications and source records attributed to Dhand, A. P..

3 recordsLinked to original sources

Synovial fibroblasts support vascular function in an acute injury-on-a-chip model

Most patients who sustain an acute joint injury develop degenerative joint disease, or osteoarthritis (OA). Animal models have informed the design of OA therapeutics; however, no disease-modifying therapy has successfully translated to human patients. Thus, there is a strong motivation to develop humanized in vitro platforms to fill a critical gap in knowledge of disease progression post-injury. Here, we develop an acute injury-on-a-chip model of the synovium, a vascularized, joint-lining tissue that has been implicated in OA progression and as a key driver of joint disease. We apply this chip-based system to investigate crosstalk between endothelial cells, lining an engineered vessel, and synovial fibroblasts, embedded within an extracellular matrix hydrogel. Our data indicate that synovial fibroblasts, rather than initiating disease, attempt to support and maintain vascular function in the presence of acute inflammation (i.e., interleukin-1{beta}). Such knowledge may provide new targets for OA therapeutics, preventing the progression from joint injury to disease in patients. TeaserIn the presence of inflammation, a hallmark of acute injury, synovial fibroblasts work to maintain vascular health.

bioengineering↗

Cytoplasmic CaMKIIδ-B prevents myocardial recovery in heart failure

Restoration of cardiac function in patients with advanced heart failure is rare, and the molecular processes that regulate recovery are unknown. To identify potential mechanisms, we studied paired myocardial samples before and after left ventricular assist device therapy, where significant cardiac functional recovery occurred in [~]25% of patients. We found that expression of the nuclear B isoform of Ca2+/calmodulin-dependent protein kinase II{delta} (CaMKII{delta}-B) inversely correlated with recovery. Furthermore, increased phosphorylation near the CaMKII{delta}-B nuclear localization signal in non-responders prevented its auto-activation dependent nuclear translocation. Expression of a cytoplasm-restricted CaMKII{delta}-B in cardiomyocytes dramatically remodeled the phospho-proteome and impaired contractility, while a nuclear-competent version did not. Modulating CaMKII{delta} subcellular localization may thus represent a therapeutic strategy for advanced heart failure.

physiology↗

Digital Light Processing 3D Printing enables High Throughput Fabrication of Human Engineered Heart Tissues for Disease Modeling

3D in vitro engineered heart tissue (EHT) models recapitulate aspects of native cardiac physiology but are often limited by scalability, cost, and reproducibility. Here, we report a simple, one-step method for rapid ([~]minutes) fabrication of molds using digital light processing (DLP)-based 3D printing that support the formation of EHTs by human induced pluripotent stem cell derived cardiomyocytes (iPSC-CMs) with high reproducibility (>95% efficiency) and varied designs (e.g., length, aspect ratio). Compared to 2D iPSC-CMs, 3D EHTs display enhanced maturity, including increased expression of {beta}-oxidation genes, higher concentrations of sarcomeric myosins, improved sarcomere density and alignment, and enrichment of cardiac pathways (e.g., upregulation of sodium channels, action potentials, contraction). The technology is applied to model pathological cardiac hypertrophy in vitro, using either (i) acute adrenergic agonism or (ii) chronic culture within stiff hydrogel molds. Treated EHTs exhibit increased levels of pathology-associated gene expression and activation of signaling cascades involved in pathological remodeling compared to untreated controls or treated 2D iPSC-CMs. Thus, our method results in robust yet simpler, cheaper, and faster EHTs to study cardiac disease.

bioengineering↗