Biology subjects

Wheeler, E. E.

Publications and source records attributed to Wheeler, E. E..

4 recordsLinked to original sources

bioRxiv2026

Spatiotemporal Control of Genetic and Epigenetic Editing through Covalent Tethering of CRISPR Nanoparticles to Zwitterionic Microgels

CRISPR gene editing offers unprecedented genomic and transcriptomic control, positioning it as a powerful tool for cell therapies. Non-viral CRISPR delivery avoids the immunogenicity, genomic integration, and packaging limits of viral vectors, but local or systemic injections of non-viral nanoparticles suffers from transient action and poor biodistribution. Alternatively, biomaterial-based delivery improves nanoparticle localization and sustains delivery, yet current approaches rely on non-specific adsorption of nanoparticles to scaffolds, risking aggregation, destabilization, and unreliable release kinetics. This work establishes a novel strategy to covalently tether nanoparticles to biomaterial substrates through SnoopTag and SpyTag bioconjugation systems for spatiotemporal control of non-viral CRISPR delivery. The RALA cell-penetrating peptide, an efficient and low-cytotoxicity CRISPR delivery system, was functionalized with SnoopTag without altering nanoparticle formation or transfection capacity. SnoopTag-functionalized nanoparticles were then covalently tethered to SpyTag-decorated zwitterionic microgels via a SnoopCatcher-SpyCatcher fusion protein. This platform achieves sustained RALA-mRNA nanoparticle delivery and prolonged CRISPR activation in human mesenchymal stem cells seeded within CRISPR-loaded microgel scaffolds. This work establishes a defined biorthogonal conjugation system that tethers non-viral nanoparticles to biomaterial platforms for sustained and localized CRISPR gene editing.

bioengineering↗

bioRxiv2026

Bioorthogonal Tethering of FGF18 to Annealed Microgel Scaffolds Enhances Cartilage Repair

Articular cartilage damage often progresses to osteoarthritis (OA), a degenerative joint disease characterized by chronic pain, limited mobility, and reduced quality of life. Tissue engineering approaches using poly (ethylene glycol) (PEG)-based hydrogels offer tunable mechanical properties and bioactive functionalization, yet the influence of surface charge on cartilage regeneration remains underexplored. Moreover, recombinant fibroblast growth factor 18 (FGF18) has successfully improved cartilage tissue thickness in clinical trials, but required high dosages and recurring injections may limit compliance. Here, we developed a granular microgel-based platform with bioorthogonally tethered FGF18 to evaluate the interplay of microgel surface charge and growth factor presentation on chondrogenesis. Azide groups were incorporated onto the microgel surfaces to enable site specific FGF18 conjugation across microgel scaffolds with distinct surface charges. When seeded with mesenchymal stromal cells, microgel scaffolds functionalized with FGF18 outperformed their unmodified counterparts, evidenced by higher GAG content, collagen content, and compressive modulus. In a murine microfracture model, anionic and zwitterionic microgel scaffolds tethered with FGF18 increased cartilage regeneration compared to nonionic microgels. We detected increased collagen II content within defects treated with tethered FGF18 microgel scaffolds. This work demonstrates the role of surface charge and growth factor presentation in directing cell behavior and tissue repair, advancing the design of biomaterials for cartilage regeneration. HIGHLIGHTSO_LICovalent tethering of FGF18 to microgel surface enables localized bioactivity C_LIO_LIFGF18 tethered microgel scaffolds enhance extracellular matrix deposition and chondrogenic differentiation of murine mesenchymal stromal cells in vitro C_LIO_LILocalized FGF18 presentation improves cartilage tissue formation and mechanical properties in vivo, with anionic and zwitterionic microgel scaffolds outperforming nonionic scaffolds C_LIO_LIFGF18 presentation is a more potent stimulus than microgel surface charge for cartilage regeneration C_LI

bioengineering↗

bioRxiv2026

Dynamic Compression of Spheroid-Laden Alginate Granular Composites Induces Hypertrophic Chondrocyte Phenotype

Hypertrophic cartilage is a promising bone repair strategy by producing a mineralizable matrix that transitions to bone through endochondral ossification. Current approaches require large cell numbers and costly recombinant factors to induce chondrogenesis. Here, we developed a composite granular scaffold using photocrosslinkable alginate microgels, cell-secreted decellularized extracellular matrix (dECM), and mesenchymal stromal cell (MSC) spheroids under dynamic compressive loading for hypertrophic cartilage formation. Incorporation of dECM into MSC spheroids enhanced expression of chondrogenic markers and supported the hypertrophic phenotype, evidenced by increased VEGFA and SPP1 expression and ALP activity. Dynamic loading further increased spheroid sprouting and scaffold mineralization. Histology confirmed mature hypertrophic cartilage conducive to bone formation. Upregulation of hypertrophic and osteogenic markers was associated with YAP1 activation, linking compressive loading to mechanotransduction to drive hypertrophic cartilage formation. These results demonstrate that dynamic compressive loading, cell aggregates, and scaffold granular macroporosity synergistically yield hypertrophic cartilage.

bioengineering↗

bioRxiv2025

Basigin Links Altered Skeletal Stem Cell Lineage Dynamics with Glucocorticoid-induced Bone Loss and Impaired Angiogenesis

Glucocorticoid (GC) induced osteoporosis (GIOP) and osteonecrosis remain a significant health issue with few approved therapies that can treat the bone loss and dysfunction of skeletal vasculature. Therefore, we aimed to investigate the cellular and molecular processes by which GCs affect osteogenesis and angiogenesis, as well as how treatment with parathyroid hormone (hPTH 1-34) modifies these effects in a mouse model of GIOP. GC treatment reduced bone mass through decreased bone formation by skeletal stem cells (SSCs) while also increasing osteoclast mediated resorption. Concomitantly, endothelial cells were increased in numbers but displayed distorted phenotypical features. However, hPTH treatment reversed GC induced changes in osteogenesis and angiogenesis to control levels. Transplantation studies of SSCs combined with molecular analysis by single cell RNA-sequencing and functional testing of primary human cells tied GC-induced skeletal changes to altered stem and progenitor cell differentiation dynamics. This in turn perpetuated reduced osteogenesis and vascular malformation through direct SSC-endothelial crosstalk mediated at least in part by Basigin. Intriguingly, antibody-mediated blockade of Basigin during GC treatment prevented detrimental bone loss. In addition, when administered to aged mice, anti-Basigin therapy reinstated bone remodeling to significantly improve bone mass independent of sex. These findings, while helping to explain the cellular and molecular basis of how hPTH treatment can mitigate GC induced bone loss, provide new therapeutic vantage points for GIOP and other conditions associated with bone loss.

cell biology↗