Do working parents in the United States expect work location to impact job and family satisfaction in the post-pandemic period? Evidence from a survey experiment.

The pandemic response allowed many parents in the United States and globally to work remotely for the first time ever which, for many, continued into the recovery. It is unclear whether, after a period when a large segment of the United States labor force worked remotely, remote work is viewed favorably or unfavorably among employed parents. We present results from a survey experiment assessing whether employed parents in the United States perceive that remote work will impact a hypothetical employed parents' job and family satisfaction and, critically, whether perceptions of work-family conflict and anticipated job rewards mediate this relationship. We find that respondents who are also employed parents perceive that hypothetical employed parents who access remote work will report lower job satisfaction and higher family satisfaction. Perceptions of work-family conflict do not mediate this association. Rather, we find that job rewards (e.g., pay, promotion, etc.) fully mediate the relationship between remote work and perceived job satisfaction. Ultimately, this indicates that employed parents perceive that remote work will bring workers like them less pay and thus lower job satisfaction but greater family satisfaction. This extends arguments about remote work in the light of the conceptualization of a flexibility stigma and a flexibility paradox. Implications for practice and theory are discussed.

Ketoprofen-Based Polymer-Drug Nanoparticles Provide Anti-Inflammatory Properties to HA/Collagen Hydrogels.

Current limitations of wound dressings for treating chronic wounds require the development of novel approaches. One of these is the immune-centered approach, which aims to restore the pro-regenerative and anti-inflammatory properties of macrophages. Under inflammatory conditions, ketoprofen nanoparticles (KT NPs) can reduce pro-inflammatory markers of macrophages and increase anti-inflammatory cytokines. To assess their suitability as part of wound dressings, these NPs were combined with hyaluronan (HA)/collagen-based hydro- (HGs) and cryogels (CGs). Different HA and NP concentrations and loading techniques for NP incorporation were used. The NP release, gel morphology, and mechanical properties were studied. Generally, colonialization of the gels with macrophages resulted in high cell viability and proliferation. Furthermore, direct contact of the NPs to the cells reduced the level of nitric oxide (NO). The formation of multinucleated cells on the gels was low and further decreased by the NPs. For the HGs that produced the highest reduction in NO, extended ELISA studies showed reduced levels of the pro-inflammatory markers PGE2, IL-12 p40, TNF-α, and IL-6. Thus, HA/collagen-based gels containing KT NPs may represent a novel therapeutic approach for treating chronic wounds. Whether effects observed in vitro translate into a favorable profile on skin regeneration in vivo will require rigorous testing.

Microdialysis Reveals Anti-Inflammatory Effects of Sulfated Glycosaminoglycanes in the Early Phase of Bone Healing.

Although chronic inflammation inhibits bone healing, the healing process is initiated by an inflammatory phase. In a well-tuned sequence of molecular events, pro-inflammatory cytokines are secreted to orchestrate the inflammation response to injury and the recruitment of progenitor cells. These events in turn activate the secretion of anti-inflammatory signaling molecules and attract cells and mediators that antagonize the inflammation and initiate the repair phase. Sulfated glycosaminoglycanes (sGAG) are known to interact with cytokines, chemokines and growth factors and, thus, alter the availability, duration and impact of those mediators on the local molecular level. sGAG-coated polycaprolactone-co-lactide (PCL) scaffolds were inserted into critical-size femur defects in adult male Wistar rats. The femur was stabilized with a plate, and the defect was filled with either sGAG-containing PCL scaffolds or autologous bone (positive control). Wound fluid samples obtained by microdialysis were characterized regarding alterations of cytokine concentrations over the first 24 h after surgery. The analyses revealed the inhibition of the pro-inflammatory cytokines IL-1ß and MIP-2 in the sGAG-treated groups compared to the positive control. A simultaneous increase of IL-6 and TNF-α indicated advanced regenerative capacity of sGAG, suggesting their potential to improve bone healing.

Impact of Sulfated Hyaluronan on Bone Metabolism in Diabetic Charcot Neuroarthropathy and Degenerative Arthritis.

Bone in diabetes mellitus is characterized by an altered microarchitecture caused by abnormal metabolism of bone cells. Together with diabetic neuropathy, this is associated with serious complications including impaired bone healing culminating in complicated fractures and dislocations, especially in the lower extremities, so-called Charcot neuroarthropathy (CN). The underlying mechanisms are not yet fully understood, and treatment of CN is challenging. Several in vitro and in vivo investigations have suggested positive effects on bone regeneration by modifying biomaterials with sulfated glycosaminoglycans (sGAG). Recent findings described a beneficial effect of sGAG for bone healing in diabetic animal models compared to healthy animals. We therefore aimed at studying the effects of low- and high-sulfated hyaluronan derivatives on osteoclast markers as well as gene expression patterns of osteoclasts and osteoblasts from patients with diabetic CN compared to non-diabetic patients with arthritis at the foot and ankle. Exposure to sulfated hyaluronan (sHA) derivatives reduced the exaggerated calcium phosphate resorption as well as the expression of genes associated with bone resorption in both groups, but more pronounced in patients with CN. Moreover, sHA derivatives reduced the release of pro-inflammatory cytokines in osteoclasts of patients with CN. The effects of sHA on osteoblasts differed only marginally between patients with CN and non-diabetic patients with arthritis. These results suggest balancing effects of sHA on osteoclastic bone resorption parameters in diabetes.

Sulfated glycosaminoglycans inhibit transglutaminase 2 by stabilizing its closed conformation.

Transglutaminases (TGs) catalyze the covalent crosslinking of proteins via isopeptide bonds. The most prominent isoform, TG2, is associated with physiological processes such as extracellular matrix (ECM) stabilization and plays a crucial role in the pathogenesis of e.g. fibrotic diseases, cancer and celiac disease. Therefore, TG2 represents a pharmacological target of increasing relevance. The glycosaminoglycans (GAG) heparin (HE) and heparan sulfate (HS) constitute high-affinity interaction partners of TG2 in the ECM. Chemically modified GAG are promising molecules for pharmacological applications as their composition and chemical functionalization may be used to tackle the function of ECM molecular systems, which has been recently described for hyaluronan (HA) and chondroitin sulfate (CS). Herein, we investigate the recognition of GAG derivatives by TG2 using an enzyme-crosslinking activity assay in combination with in silico molecular modeling and docking techniques. The study reveals that GAG represent potent inhibitors of TG2 crosslinking activity and offers atom-detailed mechanistic insights.

Sulfated hyaluronic acid inhibits the hyaluronidase CEMIP and regulates the HA metabolism, proliferation and differentiation of fibroblasts.

Hyaluronan (HA) is an extracellular matrix component that regulates a variety of physiological and pathological processes. The function of HA depends both on its overall amount and on its size, properties that are controlled by HA synthesizing and degrading enzymes. The lack of inhibitors that can specifically block individual HA degrading enzymes has hampered attempts to understand the contribution of individual hyaluronidases to different physiological and pathological processes. CEMIP is a recently discovered hyaluronidase that cleaves HA through mechanisms and under conditions that are distinct from those of other hyaluronidases such as HYAL1 or HYAL2. The role of its hyaluronidase activity in physiology and disease is poorly understood. Here, we characterized a series of sulfated HA derivatives (sHA) with different sizes and degrees of sulfation for their ability to inhibit specific hyaluronidases. We found that highly sulfated sHA derivatives potently inhibited CEMIP hyaluronidase activity. One of these compounds, designated here as sHA3.7, was characterized further and shown to inhibit CEMIP with considerable selectivity over other hyaluronidases. Inhibition of CEMIP with sHA3.7 in fibroblasts, which are the main producers of HA in the interstitial matrix, increased the cellular levels of total and high molecular weight HA, while decreasing the fraction of low molecular weight HA fragments. Genetic deletion of CEMIP in mouse embryonic fibroblasts (MEFs) produced analogous results and confirmed that the effects of sHA3.7 on HA levels were mediated by CEMIP inhibition. Importantly, both CEMIP deletion and its inhibition by sHA3.7 suppressed fibroblast proliferation, while promoting differentiation into myofibroblasts, as reflected in a lack of CEMIP in myofibroblasts within skin wounds in experimental mice. By contrast, adipogenic and osteogenic differentiation were attenuated upon CEMIP loss or inhibition. Our results demonstrate the importance of CEMIP for the HA metabolism, proliferation and differentiation of fibroblasts, and suggest that inhibition of CEMIP with sulfated HA derivatives such as sHA3.7 has potential utility in pathological conditions that are dependent on CEMIP function.

High-Sulfated Glycosaminoglycans Prevent Coronavirus Replication.

Coronaviruses (CoVs) are common among humans and many animals, causing respiratory or gastrointestinal diseases. Currently, only a few antiviral drugs against CoVs are available. Especially for SARS-CoV-2, new compounds for treatment of COVID-19 are urgently needed. In this study, we characterize the antiviral effects of two high-sulfated glycosaminoglycan (GAG) derivatives against SARS-CoV-2 and bovine coronaviruses (BCoV), which are both members of the Betacoronavirus genus. The investigated compounds are based on hyaluronan (HA) and chondroitin sulfate (CS) and exhibit a strong inhibitory effect against both CoVs. Yield assays were performed using BCoV-infected PT cells in the presence and absence of the compounds. While the high-sulfated HA (sHA3) led to an inhibition of viral growth early after infection, high-sulfated CS (sCS3) had a slightly smaller effect. Time of addition assays, where sHA3 and sCS3 were added to PT cells before, during or after infection, demonstrated an inhibitory effect during all phases of infection, whereas sHA3 showed a stronger effect even after virus absorbance. Furthermore, attachment analyses with prechilled PT cells revealed that virus attachment is not blocked. In addition, sHA3 and sCS3 inactivated BCoV by stable binding. Analysis by quantitative real-time RT PCR underlines the high potency of the inhibitors against BCoV, as well as B.1-lineage, Alpha and Beta SARS-CoV-2 viruses. Taken together, these results demonstrated that the two high-sulfated GAG derivatives exhibit low cytotoxicity and represent promising candidates for an anti-CoV therapy.

Artificial Extracellular Matrices Containing Bioactive Glass Nanoparticles Promote Osteogenic Differentiation in Human Mesenchymal Stem Cells.

The present study analyzes the capacity of collagen (coll)/sulfated glycosaminoglycan (sGAG)-based surface coatings containing bioactive glass nanoparticles (BGN) in promoting the osteogenic differentiation of human mesenchymal stroma cells (hMSC). Physicochemical characteristics of these coatings and their effects on proliferation and osteogenic differentiation of hMSC were investigated. BGN were stably incorporated into the artificial extracellular matrices (aECM). Oscillatory rheology showed predominantly elastic, gel-like properties of the coatings. The complex viscosity increased depending on the GAG component and was further elevated by adding BGN. BGN-containing aECM showed a release of silicon ions as well as an uptake of calcium ions. hMSC were able to proliferate on coll and coll/sGAG coatings, while cellular growth was delayed on aECM containing BGN. However, a stimulating effect of BGN on ALP activity and calcium deposition was shown. Furthermore, a synergistic effect of sGAG and BGN was found for some donors. Our findings demonstrated the promising potential of aECM and BGN combinations in promoting bone regeneration. Still, future work is required to further optimize the BGN/aECM combination for increasing its combined osteogenic effect.

Identification of intracellular glycosaminoglycan-interacting proteins by affinity purification mass spectrometry.

Glycosaminoglycans (GAGs) are essential functional components of the extracellular matrix (ECM). Artificial GAGs like sulfated hyaluronan (sHA) exhibit pro-osteogenic properties and boost healing processes. Hence, they are of high interest for supporting bone regeneration and wound healing. Although sulfated GAGs (sGAGs) appear intracellularly, the knowledge about intracellular effects and putative interaction partners is scarce. Here we used an affinity-purification mass spectrometry-based (AP-MS) approach to identify novel and particularly intracellular sGAG-interacting proteins in human bone marrow stromal cells (hBMSC). Overall, 477 proteins were found interacting with at least one of four distinct sGAGs. Enrichment analysis for protein localization showed that mainly intracellular and cell-associated interacting proteins were identified. The interaction of sGAG with α2-macroglobulin receptor-associated protein (LRPAP1), exportin-1 (XPO1), and serine protease HTRA1 (HTRA1) was confirmed in reverse assays. Consecutive pathway and cluster analysis led to the identification of biological processes, namely processes involving binding and processing of nucleic acids, LRP1-dependent endocytosis, and exosome formation. Respecting the preferentially intracellular localization of sGAG in vesicle-like structures, also the interaction data indicate sGAG-specific modulation of vesicle-based transport processes. By identifying many sGAG-specific interacting proteins, our data provide a resource for upcoming studies aimed at molecular mechanisms and understanding of sGAG cellular effects.

Chemically modified glycosaminoglycan derivatives as building blocks for biomaterial coatings and hydrogels.

Tissue regeneration is regulated by the cellular microenvironment, e.g. the extracellular matrix. Here, sulfated glycosaminoglycans (GAG), are of vital importance interacting with mediator proteins and influencing their biological activity. Hence, they are promising candidates for controlling tissue regeneration. This review addresses recent achievements regarding chemically modified GAG as well as collagen/GAG-based coatings and hydrogels including (i) chemical functionalization strategies for native GAG, (ii) GAG-based biomaterial strategies for controlling cellular responses, (iii) (bio)chemical methods for characterization and iv) protein interaction profiles and attained tissue regeneration in vitro and in vivo. The potential of GAG for bioinspired, functional biomaterials is highlighted.

Collagen/hyaluronan based hydrogels releasing sulfated hyaluronan improve dermal wound healing in diabetic mice via reducing inflammatory macrophage activity.

Sustained inflammation associated with dysregulated macrophage activation prevents tissue formation and healing of chronic wounds. Control of inflammation and immune cell functions thus represents a promising approach in the development of advanced therapeutic strategies. Here we describe immunomodulatory hyaluronan/collagen (HA-AC/coll)-based hydrogels containing high-sulfated hyaluronan (sHA) as immunoregulatory component for the modulation of inflammatory macrophage activities in disturbed wound healing. Solute sHA downregulates inflammatory activities of bone marrow-derived and tissue-resident macrophages in vitro. This further affects macrophage-mediated pro-inflammatory activation of skin cells as shown in skin ex-vivo cultures. In a mouse model of acute skin inflammation, intradermal injection of sHA downregulates the inflammatory processes in the skin. This is associated with the promotion of an anti-inflammatory gene signature in skin macrophages indicating a shift of their activation profile. For in vivo translation, we designed HA-AC/coll hydrogels allowing delivery of sHA into wounds over a period of at least one week. Their immunoregulatory capacity was analyzed in a translational experimental approach in skin wounds of diabetic db/db mice, an established model for disturbed wound healing. The sHA-releasing hydrogels improved defective tissue repair with reduced inflammation, augmented pro-regenerative macrophage activation, increased vascularization, and accelerated new tissue formation and wound closure.

A Versatile Macromer-Based Glycosaminoglycan (sHA3) Decorated Biomaterial for Pro-Osteogenic Scavenging of Wnt Antagonists.

High serum levels of Wnt antagonists are known to be involved in delayed bone defect healing. Pharmaceutically active implant materials that can modulate the micromilieu of bone defects with regard to Wnt antagonists are therefore considered promising to support defect regeneration. In this study, we show the versatility of a macromer based biomaterial platform to systematically optimize covalent surface decoration with high-sulfated glycosaminoglycans (sHA3) for efficient scavenging of Wnt antagonist sclerostin. Film surfaces representing scaffold implants were cross-copolymerized from three-armed biodegradable macromers and glycidylmethacrylate and covalently decorated with various polyetheramine linkers. The impact of linker properties (size, branching) and density on sHA3 functionalization efficiency and scavenging capacities for sclerostin was tested. The copolymerized 2D system allowed for finding an optimal, cytocompatible formulation for sHA3 functionalization. On these optimized sHA3 decorated films, we showed efficient scavenging of Wnt antagonists DKK1 and sclerostin, whereas Wnt agonist Wnt3a remained in the medium of differentiating SaOS-2 and hMSC. Consequently, qualitative and quantitative analysis of hydroxyapatite staining as a measure for osteogenic differentiation revealed superior mineralization on sHA3 materials. In conclusion, we showed how our versatile material platform enables us to efficiently scavenge and inactivate Wnt antagonists from the osteogenic micromilieu. We consider this a promising approach to reduce the negative effects of Wnt antagonists in regeneration of bone defects via sHA3 decorated macromer based macroporous implants.

Peptide-mediated surface coatings for the release of wound-healing cytokines.

Supporting the wound healing process by sending the appropriate cytokine signals can shorten healing time and overcome chronic inflammation syndromes. Even though adhesion peptides consisting of Arg-Gly-Asp (RGD) are commonly used to enhance cell-surface interactions, peptide-mediated cytokine delivery has not been widely exploited so far. Cytokines interact with high affinity with their cognitive receptors but also with sulfated glycosaminoglycans (GAGs), both of which form a base for incorporation of cytokines into functional biomaterials. Here, we report on a mussel-derived surface coating as a prospective cytokine delivery system using covalently bound heparin mimetics, receptor-derived chemokine-binding peptides, and heparin-binding peptides (HBP). The latter enabled non-covalent immobilization of heparin on the surface followed by chemokine binding and release, whereas the former allowed direct non-covalent chemokine immobilization. The peptide displayed excellent binding to custom-made polystyrene 96-well plates, enabling convenient testing of several compounds. Released chemokine successfully induced migration in Jurkat cells, especially for the non-covalent heparin immobilization approach using HBPs as evaluated in a transwell assay. In comparison, heparin-mimetic coatings, comprised of sulfated peptides and GAG derivatives, proved less efficient with respect to amount of immobilized chemokine and migratory response. Thus, our study provides a roadmap for further rational optimization and translation into clinics.

The influence of different artificial extracellular matrix implant coatings on the regeneration of a critical size femur defect in rats.

Resorbable biomaterials based on artificial extracellular matrices (aECM) represent promising scaffolds for the treatment of large bone defects. Here, we investigated various glycosaminoglycan (GAG) derivatives of varying sulfation degree with respect to their influence on in vivo bone healing. The materials used in this study consisted of GAG-coated degradable polycaprolactone-co-lactide (PCL). Critical size femur defects in rats were filled with autologous bone serving as positive control or the respective coated or uncoated PCL scaffolds. After 2 and 12 weeks, progress in the healing process was investigated by analyzing the new bone matrix formation, the collagen content and hydroxyapatite formation by using micro-computed tomography (µCT), biomechanical testing, nuclear magnetic resonance spectroscopy (NMR) and histology. The sulfated GAG coating contributed substantially to bone regeneration, increased collagen synthesis and initiated mineralization of the organic matrix. Most substantial collagen production was detected in scaffolds coated with chondroitin sulfate. Scaffolds coated with hypersulfated hyaluronan induced formation of new bone volume comparable to what was observed in the positive control. GAG differing in the sugar backbone and degree of sulfation modulate the healing process at different times, eventually leading to improved bone healing.

Biomimetic tissue models reveal the role of hyaluronan in melanoma proliferation and invasion.

Interactions of hyaluronan (HA) and tumor and stromal cells are highly discussed as one of the major contributors in tumor progression and metastasis. The balance of HA in the tissue is highly regulated by two key enzyme classes; hyaluronan synthases (HAS) and hyaluronidases (HYAL). Current reports hint that the HA amount in the tissue is correlated with poor prognosis in melanoma, the most life-threatening skin tumor. In this work, we generated in vivo mouse models with low and high expression of Has2 and used the models for studying melanoma proliferation of the B78D14 melanoma cell line. We found that a strong reduction of HA amount in the skin was correlated to decreased tissue stiffness and a reduction in tumor weight. Since tumor cells have a direct contact to the HA in the tumor and at the stroma interface, we reconstituted different biomimetic in vitro models using fibroblasts derived from a mouse model to recapitulate melanoma cell behavior at the tumor boundary, namely, (i) decellularized fibroblast matrix (FbECM), (ii) fibroblast embedded into 3D collagen matrices (FbColl), and (iii) well-defined HA-functionalized 3D collagen matrices (HAColl). We found no considerable effect of high and low amounts of fibroblast-derived HA in the matrices on melanoma proliferation and invasion. However, HYAL1-treated FbECM and FbColl, as well as HAColl functionalized with low molecular weight HA (34 kDa) promoted proliferation and invasion of melanoma cells in a concentration dependent manner. Our results emphasize the molecular weight specific effects of HA in regulation of melanoma behavior and provide an alternative explanation for the in vivo observation of HA dependent tumor growth.

Dual Action of Sulfated Hyaluronan on Angiogenic Processes in Relation to Vascular Endothelial Growth Factor-A.

Pathological healing characterized by abnormal angiogenesis presents a serious burden to patients' quality of life requiring innovative treatment strategies. Glycosaminoglycans (GAG) are important regulators of angiogenic processes. This experimental and computational study revealed how sulfated GAG derivatives (sGAG) influence the interplay of vascular endothelial growth factor (VEGF)165 and its heparin-binding domain (HBD) with the signaling receptor VEGFR-2 up to atomic detail. There was profound evidence for a HBD-GAG-HBD stacking configuration. Here, the sGAG act as a "molecular glue" leading to recognition modes in which sGAG interact with two VEGF165-HBDs. A 3D angiogenesis model demonstrated the dual regulatory role of high-sulfated derivatives on the biological activity of endothelial cells. While GAG alone promote sprouting, they downregulate VEGF165-mediated signaling and, thereby, elicit VEGF165-independent and -dependent effects. These findings provide novel insights into the modulatory potential of sGAG derivatives on angiogenic processes and point towards their prospective application in treating abnormal angiogenesis.

Biomaterials in repairing rat femoral defects: In vivo insights from small animal positron emission tomography/computed tomography (PET/CT) studies.

Biomaterials coated with artificial extracellular matrices (aECM) are intended to support the healing of critical size bone defects. This pilot study investigated (i) the feasibility of dual-tracer PET/CT imaging for functional characterization of biomaterial-assisted bone healing in a rat femoral defect model and (ii) the bone healing ability of polycaprolactone-co-lactide (PCL) scaffolds, coated with various aECM consisting of collagen type I (Col) and glycosaminoglycans (GAGs) such as chondroitin sulfate (CS) or polysulfated hyaluronan (sHA3). [18F]FDG and [18F]fluoride PET 4 and 8 weeks after implantation of aECM-coated PCL scaffolds, which provide an in vivo measure of cellular activation and bone mineralization, respectively, combined with CT imaging (in vivo/ex vivo) and histological/immunohistochemical investigations (ex vivo) showed that coating with CS in particular is beneficial for bone healing. The possible involvement of COX-2 and TGase 2, key enzymes of inflammation and ECM remodeling, in these processes offers starting points for targeted adjuvant therapy in the course of various bone healing phases. Our investigations show the feasibility of the selected dual-tracer approach for PET/CT imaging. In principle, this approach can be extended by further PET tracers for the functional characterization of physiological processes such as hypoxia/reperfusion or selected molecular players.

Glycosaminoglycans influence enzyme activity of MMP2 and MMP2/TIMP3 complex formation - Insights at cellular and molecular level.

The extracellular matrix (ECM) is a highly dynamic network constantly remodeled by a fine-tuned protein formation and degradation balance. Matrix metalloproteinases (MMPs) constitute key orchestrators of ECM degradation. Their activity is controlled by tissue inhibitors of metalloproteinases (TIMPs) and glycosaminoglycans (GAG). Here, we investigated the molecular interplay of MMP2 with different GAG (chondroitin sulfate, hyaluronan (HA), sulfated hyaluronan (SH) and heparin (HE)) and the impact of GAG on MMP2/TIMP3 complex formation using in vitro-experiments with human bone marrow stromal cells, in silico docking and molecular dynamics simulations. SH and HE influenced MMP2 and TIMP3 protein levels and MMP2 activity. Only SH supported the alignment of both proteins in fibrillar-like structures, which, based on our molecular models, would be due to a stabilization of the interactions between MMP2-hemopexin domain and TIMP3-C-terminal tail. Dependent on the temporal sequential order in which the final ternary complex was formed, our models indicated that SH and HA can affect TIMP3-induced MMP2 inhibition through precluding or supporting their interactions, respectively. Our combined experimental and theoretical approach provides valuable new insights on how GAG interfere with MMP2 activity and MMP2/TIMP3 complex formation. The results obtained evidence GAG as promising molecules for fine-balanced intervention of ECM remodeling.

Sulfated hyaluronan-containing artificial extracellular matrices promote proliferation of keratinocytes and melanotic phenotype of melanocytes from the outer root sheath of hair follicles.

The aim of this work was to establish improved cultivation conditions for human keratinocytes (HUKORS) and melanocytes (HUMORS) from the outer root sheath (ORS) of human hair follicles for purposes of generating an epidermal graft. To this end, the cells were cultivated on artificial extracellular matrix coatings composed of collagen (COLL) and hyaluronan (HA) with varying sulfation degrees. HUKORS and HUMORS were characterized based on their morphology and proliferation, marker gene expression, protein expression and melanin content in melanocytes. Depending on the sulfation degree, the matrices provided a favorable proliferation environment for HUKORS and improved the balance between proliferation and the exertion of melanotic phenotype (gene expression and melanin content) in HUMORS. Based on the increased gene expression of microphthalmia-associated transcription factor, as well as the downstream-affected melanotic genes premelanosome protein and tyrosinase in HUMORS cultivated on collagen matrices with high-sulfated HA, we assume that sulfated HA enhanced melanotic phenotype either by directly binding the CD44 receptor or by concentrating signaling mediators on site. Being a promising cultivation environment for both HUKORS and HUMORS, collagen matrices with sulfated HA have a potential of significantly improving the development of ORS-based epidermal grafts. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 1640-1653, 2019.