Biology subjects

Karaoglu, I. C.

Publications and source records attributed to Karaoglu, I. C..

3 recordsLinked to original sources

bioRxiv2025

Single-gene knockout of RNLS or HIVEP2 are insufficient to protect β-cell spheroids from allo- and xeno-rejection

Type 1 diabetes can be cured by {beta}-cell replacement in principle, yet recurrent autoimmunity and transplantation barriers rapidly destroy implanted cells. Genome-wide CRISPR screening by Cai et al. highlighted RNLS and HIVEP2 as candidate genes, but their value outside an autoimmune setting is unknown. Here, it was evaluated whether single-gene knockout of RNLS or HIVEP2 could similarly protect {beta}-cell grafts against allo- and xenogeneic rejection. Murine {beta}-TC-6 and human EndoC-{beta}H1 cell lines were genetically edited using CRISPR-Cas9 to knockout RNLS or HIVEP2, and editing efficiencies were confirmed via T7 endonuclease I assay and TIDE analysis. Functional characterization indicated that RNLS deletion modestly impaired glucose-stimulated insulin secretion in murine cells, whereas HIVEP2 deletion showed no functional alterations in either cell line. For in vivo assessment, genetically edited {beta}-cell spheroids were subcutaneously transplanted into CD-1 mice to model allo- (murine {beta}-cells) and xenogeneic (human {beta}-cells) rejection scenarios. Bioluminescence imaging revealed no protective effects of RNLS or HIVEP2 deletion, with grafts from both knockout groups displaying identical rejection kinetics compared to controls. These findings indicate that single-gene deletions of RNLS or HIVEP2 are insufficient for conferring meaningful protection against allo- or xenorejection, highlighting the necessity for combinatorial genome editing strategies or complementary biomaterial-based immunomodulation to achieve effective and sustained {beta}-cell graft survival.

bioengineering↗

bioRxiv2025

Effect of Photoinitiation Process on Photo-Crosslinking of Gelatin Methacryloyl Hydrogel Networks

Gelatin methacryloyl (GelMA) has emerged as a widely utilized biomaterial in tissue engineering due to its tunable mechanical properties, cell-adhesive motifs, and photo-crosslinkability. However, the physicochemical characteristics and biomedical utility of GelMA hydrogels are greatly influenced by the choice and concentration of photoinitiating systems. Despite the increasing acceptance of visible-light and UV-sensitive initiators, a systematic comparative evaluation of their impact on GelMA hydrogel properties remains limited. In this study, we present the first systematic investigation of how individual photoinitiators, Eosin Y (EY), Lithium Phenyl-2,4,6-trimethylbenzoylphosphinate (LAP), Ruthenium (II) trisbipyridyl chloride ([RuII(bpy)3]2+) (Ru), affect the viscoelastic properties, swelling behavior, degradation kinetics, and cytocompatibility of 5% and 10% (w/v) GelMA hydrogels. By varying photoinitiator concentrations ([EY]: 0.005-0.1 mM, [LAP]: 0.01-0.5% (w/v), [Ru]: 0.02-1 mM) and utilizing consistent light intensity (10 mW/cm2 at system-specific wavelengths), we identified critical thresholds and plateau behaviors that distinctly influenced the stiffness and integrity of the hydrogels. Our findings revealed that each photoinitiating system exhibits unique advantages and trade-offs. LAP and Ru systems facilitated rapid gelation with easier utilization and were associated with higher swelling and accelerated degradation profiles--features particularly advantageous for applications such as 3D bioprinting and in situ injectable hydrogel systems. However, their atypical behaviors at certain concentrations and light exposure durations highlight the necessity for precise control and further mechanistic exploration. In contrast, EY-mediated hydrogels offered superior stiffness and minimal swelling at optimal concentrations, favoring applications that demand long-term mechanical stability, at the cost of a more complex cross-linking mechanism. Notably, by correlating mechanical and degradation behaviors with NIH-3T3 fibroblast viability, we also assessed biocompatibility window for each concentration of the systems, linking biomaterial performance with biomedical applicability. Overall, our study underlines the importance of tailoring photoinitiator selection and concentration to specific application needs, striking a balance between gelation kinetics, mechanical integrity, degradation behavior, and cytocompatibility. These insights provide a foundational framework for engineering GelMA-based hydrogels paving the way for reproducible, efficient, targeted biomedical applications. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=114 SRC="FIGDIR/small/648118v1_ufig1.gif" ALT="Figure 1"> View larger version (26K): org.highwire.dtl.DTLVardef@1286f72org.highwire.dtl.DTLVardef@1aca5f6org.highwire.dtl.DTLVardef@1c3bc63org.highwire.dtl.DTLVardef@1850c97_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2023

Extracellular matrix sulfation in the tumor microenvironment stimulates cancer stemness and invasiveness

Tumor extracellular matrices (ECM) exhibit aberrant changes in composition and mechanics compared to normal tissues. Proteoglycans (PG) are vital regulators of cellular signaling in the ECM with ability to modulate receptor tyrosine kinase (RTK) activation via their sulfated glycosaminoglycan (sGAG) side chains. However, their role on tumor cell behavior is controversial. Here, we demonstrate that PGs are heavily expressed in lung adenocarcinoma patients in correlation with invasive phenotype and poor prognosis. We developed a bioengineered human lung tumor model which recapitulates the increase of sGAGs in tumors in an organotypic matrix with independent control of stiffness, viscoelasticity, ligand density and porosity. Our model reveals that increased sulfation stimulates extensive proliferation, epithelial-mesenchymal transition and stemness in cancer cells. We identified the FAK-PI3K-mTOR signaling axis as a mediator of sulfation-induced molecular changes in cells upon activation of a distinct set of RTKs within tumor-mimetic hydrogels. We demonstrate that the transcriptomic landscape of tumor cells in response to increased sulfation resembles native PG-rich patient tumors through employing integrative omics and network modeling approaches.

bioengineering↗