Tethering Cells via Enzymatic Oxidative Crosslinking Enables Mechanotransduction in Non‐Cell‐Adhesive Materials

Abstract

proliferation, apoptosis, metabolism, and differentiation. [1,2] However, the variety of strategies to control cell-biomaterial interactions able to transmit mechanical cues from the microenvironment to the cells within engineered tissue constructs has remained limited and near-exclusively relied on cell adhesion. Biomaterials are typically endowed with bioligands that bind to cell adhesion molecules (CAMs; e.g., integrins, cadherins, and selectins). The integrinbinding tripeptide arginine-glycine-aspartic acid (RGD) [3] has been most commonly used as cell-adhesive moiety, but also numerous alternative cell-adhesive nucleotides, [4] peptides, [5] and proteins including antibodies [6] and amyloid-like lysozyme [7] have been explored. However, the constitutively active binding nature of these cell-adhesive bioligands has been associated with adverse effects such as increased fibrous capsule formation and chronic inflammation upon implantation. [8,9] Dynamic material modification strategies that display cell-adhesive bioligands with precise spatial and temporal control have been developed to address this challenge. However, once activated, their cell-adhesive properties are continuously active and can only be annihilated using Cell-matrix interactions govern cell behavior and tissue function by facilitating transduction of biomechanical cues. Engineered tissues often incorporate these interactions by employing cell-adhesive materials. However, using constitutively active cell-adhesive materials impedes control over cell fate and elicits inflammatory responses upon implantation. Here, an alternative cell-material interaction strategy that provides mechanotransducive properties via discrete inducible on-cell crosslinking (DOCKING) of materials, including those that are inherently non-cell-adhesive, is introduced. Specifically, tyramine-functionalized materials are tethered to tyrosines that are naturally present in extracellular protein domains via enzyme-mediated oxidative crosslinking. Temporal control over the stiffness of on-cell tethered 3D microniches reveals that DOCKING uniquely enables lineage programming of stem cells by targeting adhesome-related mechanotransduction pathways acting independently of cell volume changes and spreading. In short, DOCKING represents a bioinspired and cytocompatible cell-tethering strategy that offers new routes to study and engineer cell-material interactions, thereby advancing applications ranging from drug delivery, to cell-based therapy, and cultured meat.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adma.202102660.

Steering Stem Cell Fate within 3D Living Composite Tissues Using Stimuli‐Responsive Cell‐Adhesive Micromaterials

“…Photo‐initiated postcuring of SCMs could be controlled via the ruthenium complex concentration, thereby endowing SCMs with the capacity to predictably acquire a well‐defined physiological stiffness following exposure to a noninvasive visible light‐based trigger (Figure 5b ). In line with literature, [ 8f ] hydrogel stiffness linearly ( R 2 = 0.96) correlated with EthD‐1 staining intensity (Figure 5c ). This allowed for noninvasive visualization and quantification of SCM stiffness within composite microtissues before and after visible‐light‐induced postcuring at high spatial resolution.…”

“…Individual MSCs in hydrogel could differentiate towards the osteogenic lineage, which corresponded to previous studies focusing on stiffness‐controlled differentiation of MSCs in hydrogels (Figure 4b ). [ 8 , 34 ] Cell‐only spheroids embedded in hydrogel were characterized by negligible levels of osteogenesis, which corroborated a previous study that reported on the encapsulation of MSC spheroids in soft versus stiff hydrogels. [ 21 ] Interestingly, engineering composite microtissues where stiff SCMs are located in between MSCs not only fully rescued the osteogenic differentiation, but demonstrated a calcification level that significantly surpassed the conventional cells‐in‐hydrogel composition (Figure 4c ).…”

“…Specifically, cellular microtissues lack the designer cell–matrix interactions that control various important cell functions (e.g., via material elasticity or stress relaxation), which can be offered by biomaterials such as cell‐adhesive (e.g., RGD‐containing) hydrogels. [ 8 ] While such biomaterials have successfully been used for 2D cell culture or encapsulation of individual cells, [8a, 9] biomaterial strategies to actively control the microenvironment and guide the function of 3D cellular spheroids or organoids from within have remained largely unexplored.…”

Versatile polyphenolic platforms in regulating cell biology

“…Interestingly, Jeroen Leijten and co-workers have demonstrated the discrete inducible oncell crosslinking (DOCKING) of no-cell-adhesive tyraminefunctionalized dextran biomaterials onto stem cells via the oxidative crosslinking of phenolic moieties, enabling mechanotransduction via the a-actinin axis according to proteomic analysis, which indicates the promising role of DOCKING as a unique tool for optimizing tissue engineering applications. 136 Last but not the least, the possible undesired long-term side effects (e.g., fibrosis or calcification) of the polyphenolic systems should be considered thoroughly and carefully, particularly as implantation materials. Collectively, indebted by the advancements of chemistry and biology interdisciplinary, more kinds of bioactive and innovative polyphenolic materials are expected to be developed and explored, as well as translated into various clinical applications.…”

“…Information is collected from published works. 20,21,[135][136][137][138][139][140][141][142] crosslinked with EGCG and TA are mechanically stiffer compared to the rest. Moreover, the laser-induced graphitization of PDA could strengthen its mechanical properties and maintain multifunctionality.…”