Volume 113, Issue 5 e37928
RESEARCH ARTICLE

Mesenchymal Stromal Cell Chondrogenic Differentiation Induced by Continuous Stiffness Gradient in Photocrosslinkable Hydrogels

Sabrina C. Mierswa

Sabrina C. Mierswa

Department of Orthopaedic Surgery, UC Davis Health, Sacramento, California, USA

Department of Biomedical Engineering, University of California, Davis, California, USA

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Erika E. Wheeler

Erika E. Wheeler

Department of Orthopaedic Surgery, UC Davis Health, Sacramento, California, USA

Department of Biomedical Engineering, University of California, Davis, California, USA

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Ayla N. Apsey

Ayla N. Apsey

Department of Orthopaedic Surgery, UC Davis Health, Sacramento, California, USA

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Oju Jeon

Oju Jeon

Department of Biomedical Engineering, University of Illinois at Chicago, Chicago, Illinois, USA

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Eben Alsberg

Eben Alsberg

Department of Biomedical Engineering, University of Illinois at Chicago, Chicago, Illinois, USA

Department of Orthopaedic Surgery, University of Illinois at Chicago, Chicago, Illinois, USA

Department of Pharmacology and Regenerative Medicine, University of Illinois at Chicago, Chicago, Illinois, USA

Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, Illinois, USA

Jesse Brown Veterans Affairs Medical Center (JBVAMC), Chicago, Illinois, USA

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J. Kent Leach

Corresponding Author

J. Kent Leach

Department of Orthopaedic Surgery, UC Davis Health, Sacramento, California, USA

Department of Biomedical Engineering, University of California, Davis, California, USA

Correspondence:

J. Kent Leach ([email protected])

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First published: 11 May 2025

Funding: This work was supported by the National Institute of Dental and Craniofacial Research of the National Institutes of Health under award numbers R01 DE025899 (J.K.L., E.A.) and R01 AR079211 (J.K.L.). S.C.M. was supported by a National Institute of Arthritis and Musculoskeletal and Skin Diseases funded training program in Musculoskeletal Health Research (T32 AR079099) and the Floyd and Mary Schwall Fellowship in Medical Research. E.E.W. received support from the California Institute for Regenerative Medicine grant number EDUC4-12792 (CIRM EDUC4 Research Training Program).

Sabrina C. Mierswa and Erika E. Wheeler have shared first authorship.

ABSTRACT

Chondrogenic differentiation of stem and progenitor cells is dependent on the biophysical properties of the surrounding matrix. Current biomaterials-based approaches for chondrogenesis are limited to discrete platforms, slowing our ability to interrogate the role of mechanical cues such as substrate stiffness and other signals. Thus, novel platforms must incorporate a range of biophysical properties within a single construct to effectively assess changes in cell response. We encapsulated human mesenchymal stromal cells (MSCs) within biodegradable, photocurable oxidized, and methacrylated alginate (OMA). Cell-laden hydrogels were crosslinked when exposed to light through a grayscale photomask to form substrates with a continuous stiffness gradient. We also tested the influence of the adhesive ligand Arg-Gly-Asp (RGD) on chondrogenic differentiation. Compared to unmodified gels possessing uniform biophysical properties, RGD-modified OMA hydrogels with the same modulus promoted chondrogenic differentiation of MSCs as evidenced by gene expression, matrix deposition, and histological analysis. MSCs entrapped in OMA hydrogels exhibiting a biologically relevant stiffness gradient (2–13 kPa over 8 mm) demonstrated increased chondrogenic differentiation with increases in stiffness. MSC chondrogenic differentiation was dependent upon the ability to mechanosense the modulus of the surrounding matrix, confirmed by the addition of Latrunculin A (LatA), a soluble inhibitor of actin polymerization. These findings validate a methodology for customizing hydrogel platforms for chondrogenic differentiation and identifying the interplay of key variables to instruct cell function.

Conflicts of Interest

The authors declare no conflicts of interest.

Data Availability Statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.

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