Collagen/glycosaminoglycan-based matrices for controlling skin cell responses.

Wound healing and tissue regeneration are orchestrated by the cellular microenvironment, e.g. the extracellular matrix (ECM). Including ECM components in biomaterials is a promising approach for improving regenerative processes, e.g. wound healing in skin. This review addresses recent findings for enhanced epidermal-dermal regenerative processes on collagen (coll)/glycosaminoglycan (GAG)-based matrices containing sulfated GAG (sGAG) in simple and complex in vitro models. These matrices comprise 2D-coatings, electrospun nanofibrous scaffolds, and photo-crosslinked acrylated hyaluronan (HA-AC)/coll-based hydrogels. They demonstrated to regulate keratinocyte and fibroblast migration and growth, to stimulate melanogenesis in melanocytes from the outer root sheath (ORS) of hair follicles and to enhance the epithelial differentiation of human mesenchymal stem cells (hMSC). The matrices' suitability for delivery of relevant growth factors, like heparin-binding epidermal growth factor like growth factor (HB-EGF), further highlights their potential as bioinspired, functional microenvironments for enhancing skin regeneration.

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.

Structural insights into the modulation of PDGF/PDGFR-ß complexation by hyaluronan derivatives.

Angiogenesis is an important physiological process playing a crucial role in wound healing and cancer progression. Vascular endothelial growth factor (VEGF) and platelet derived growth factor (PDGF) are key players in angiogenesis. Based on previous findings regarding the modulation of VEGF activity by glycosaminoglycans (GAG), here we explore the interaction of hyaluronan (HA)-based GAG with PDGF and its receptor PDGFR-ß by applying molecular modeling and dynamics simulations in combination with surface plasmon resonance (SPR). Computational analysis on the interaction of oligo-hyaluronan derivatives with different sulfation pattern and functionalization shows that these GAG interact with PDGF in relevant regions for receptor recognition, and that high sulfation as well as modification with the TAMRA group convey stronger binding. On the other hand, the studied oligo-hyaluronan derivatives are predicted to scarcely recognize PDGFR-ß. SPR results are in line with the computational predictions regarding the binding pattern of HA tetrasaccharide (HA4) derivatives to PDGF and PDGFR-ß. Furthermore, our experimental results also show that the complexation of PDGF to PDGFR-ß can be modulated by HA4 derivatives. The results found open the path for considering HA4 derivatives as potential candidates to be exploited for modulation of the PDGF/PDGFR-ß signaling system in angiogenesis and related disease conditions.

How to Get Them off?-Assessment of Innovative Techniques for Generation and Detachment of Mature Osteoclasts for Biomaterial Resorption Studies.

The fusion process of mononuclear monocytes into multinuclear osteoclasts in vitro is an essential process for the study of osteoclastic resorption of biomaterials. Thereby biomaterials offer many influencing factors such as sample shape, material composition, and surface topography, which can have a decisive influence on the fusion and thus the entire investigation. For the specific investigation of resorption, it can therefore be advantageous to skip the fusion on samples and use mature, predifferentiated osteoclasts directly. However, most conventional detachment methods (cell scraper, accutase), lead to a poor survival rate of osteoclasts or to a loss of function of the cells after their reseeding. In the present study different conventional and novel methods of detachment in combination with different culture surfaces were investigated to obtain optimal osteoclast differentiation, yield, and vitality rates without loss of function. The innovative method-using thermoresponsive surfaces for cultivation and detachment-was found to be best suited. This is in particular due to its ability to maintain osteoclast activity, as proven by TRAP 5b-, CTSK-activity and resorption pits on dentin discs and decellularized osteoblast-derived matrix plates. In conclusion, it is shown, that osteoclasts can be predifferentiated on cell culture dishes and transferred to a reference biomaterial under preservation of osteoclastic resorption activity, providing biomaterial researchers with a novel tool for material characterization.

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.

Mono(2-ethylhexyl) phthalate (MEHP) and mono(2-ethyl-5-oxohexyl) phthalate (MEOHP) but not di(2-ethylhexyl) phthalate (DEHP) bind productively to the peroxisome proliferator-activated receptor γ.

RATIONALE: The most frequently occurring phthalate, di(2-ethylhexyl) phthalate (DEHP), causes adverse effects on glucose homeostasis and insulin sensitivity in several cell models and epidemiological studies. However, thus far, there is no information available on the molecular interaction of phthalates and one of the key regulators of the metabolism, the peroxisome proliferator-activated receptor gamma (PPARγ). Since the endogenous ligand of PPARγ, 15-deoxy-delta-12,14-prostaglandin J2 (15Δ-PGJ2 ), features structural similarity to DEHP and its main metabolites produced in human hepatic metabolism, mono(2-ethylhexyl) phthalate (MEHP) and mono(2-ethyl-5-oxohexyl) phthalate (MEOHP), we tested the hypothesis of direct interactions between PPARγ and DEHP or its transformation products. METHODS: Hydrogen/deuterium exchange mass spectrometry (HDX-MS) and docking were conducted to obtain structural insights into the interactions and surface plasmon resonance (SPR) analysis to reveal information about binding levels. To confirm the activation of PPARγ upon ligand binding on the cellular level, the GeneBLAzer® bioassay was performed. RESULTS: HDX-MS and SPR analyses demonstrated that the metabolites MEHP and MEOHP, but not DEHP itself, bind to the ligand binding pocket of PPARγ. This binding leads to typical activation-associated conformational changes, as observed with its endogenous ligand 15Δ-PGJ2 . Furthermore, the reporter gene assay confirmed productive interaction. DEHP was inactive up to a concentration of 14 µM, while the metabolites MEHP and MEOHP were active at low micromolar concentrations. CONCLUSIONS: In summary, this study gives structural insights into the direct interaction of PPARγ with MEHP and MEOHP and shows that the DEHP transformation products may modulate the lipid metabolism through PPARγ pathways.

Hyaluronan/collagen hydrogel matrices containing high-sulfated hyaluronan microgels for regulating transforming growth factor-ß1.

Hyaluronan (HA)-based microgels generated in a microfluidic approach, containing an artificial extracellular matrix composed of collagen and high-sulfated hyaluronan (sHA3), were incorporated into a HA/collagen-based hydrogel matrix. This significantly enhanced the retention of noncrosslinked sHA3 within the gels enabling controlled sHA3 presentation. Gels containing sHA3 bound higher amounts of transforming growth factor-ß1 (TGF-ß1) compared to pure HA/collagen hydrogels. Moreover, the presence of sHA3-containing microgels improved the TGF-ß1 retention within the hydrogels. These findings are promising for developing innovative biomaterials with adjustable sHA3 release and growth factor interaction profiles to foster skin repair, e.g., by rebalancing dysregulated TGF-ß1 levels.

The effect of interleukin-8 truncations on its interactions with glycosaminoglycans.

The chemokine interleukin-8 (IL-8, CXCL8) plays an important role in inflammatory processes and consecutive wound healing. It recruits primarily neutrophils to infection sites and stimulates their degranulation and phagocytosis in effector cells. IL-8 binds glycosaminoglycans (GAGs), a class of complex linear anionic polysaccharides often organized into diversely sulfated micro-domains, that enriches the protein concentration locally and so facilitate the formation of stable concentration gradients. In this study, we applied experimental and computational techniques to investigate the binding of wild type and truncated IL-8 variants to natural and chemically modified GAGs to gain further insight into the IL-8/GAG interaction. Circular dichroism spectroscopy of IL-8 variants did not reveal major structural changes upon GAG binding. Heparin affinity chromatography clearly demonstrates that gradual truncation of the C-terminal helix leads to decreasing affinities. Similarly, surface plasmon resonance indicates participation of both IL-8 termini in GAG binding, which strength is dependent on GAG sulfation degree. Molecular modeling suggests that C-terminal truncation of IL-8 weakens the interaction with GAGs by an alteration of IL-8 GAG binding site. Our study provides more detailed understanding of the IL-8/GAG interaction and contributes to the data of potential use for the development of biomedical implications in tissue regeneration.

Rearrangement of the Extracellular Domain/Extracellular Loop 1 Interface Is Critical for Thyrotropin Receptor Activation.

The thyroid stimulating hormone receptor (TSHR) is a G protein-coupled receptor (GPCR) with a characteristic large extracellular domain (ECD). TSHR activation is initiated by binding of the hormone ligand TSH to the ECD. How the extracellular binding event triggers the conformational changes in the transmembrane domain (TMD) necessary for intracellular G protein activation is poorly understood. To gain insight in this process, the knowledge on the relative positioning of ECD and TMD and the conformation of the linker region at the interface of ECD and TMD are of particular importance. To generate a structural model for the TSHR we applied an integrated structural biology approach combining computational techniques with experimental data. Chemical cross-linking followed by mass spectrometry yielded 17 unique distance restraints within the ECD of the TSHR, its ligand TSH, and the hormone-receptor complex. These structural restraints generally confirm the expected binding mode of TSH to the ECD as well as the general fold of the domains and were used to guide homology modeling of the ECD. Functional characterization of TSHR mutants confirms the previously suggested close proximity of Ser-281 and Ile-486 within the TSHR. Rigidifying this contact permanently with a disulfide bridge disrupts ligand-induced receptor activation and indicates that rearrangement of the ECD/extracellular loop 1 (ECL1) interface is a critical step in receptor activation. The experimentally verified contact of Ser-281 (ECD) and Ile-486 (TMD) was subsequently utilized in docking homology models of the ECD and the TMD to create a full-length model of a glycoprotein hormone receptor.

Sulfated Hyaluronan Alters the Interaction Profile of TIMP-3 with the Endocytic Receptor LRP-1 Clusters II and IV and Increases the Extracellular TIMP-3 Level of Human Bone Marrow Stromal Cells.

Sulfated glycosaminoglycans (sGAGs) modulate cellular processes via their interaction with extracellular matrix (ECM) proteins. We revealed a direct binding of tissue inhibitor of metalloproteinase-3 (TIMP-3) to the endocytic receptor low-density lipoprotein receptor-related protein (LRP-1) clusters II and IV using surface plasmon resonance. Sulfated hyaluronan (sHA) and chondroitin sulfate (sCS) derivatives interfered with TIMP-3/LRP-1 complex formation in a sulfation-dependent manner stronger than heparin. Electrostatic potential calculations suggested a competition between negatively charged GAGs and highly negatively charged complement-like domains of LRP-1 for the binding to a positively charged area of TIMP-3 as an underlying mechanism. In vitro studies revealed increased amounts of pericellular TIMP-3 in the presence of sHA as a consequence of the blocked protein uptake. GAG derivatives as part of biomaterials might post-translationally modulate TIMP-3 levels stronger than native GAGs, thus exhibiting catabolic effects on the ECM, which could prevent extensive pathological matrix degradation and promote wound healing.

Glycosaminoglycan derivatives: promising candidates for the design of functional biomaterials.

Numerous biological processes (tissue formation, remodelling and healing) are strongly influenced by the cellular microenvironment. Glycosaminoglycans (GAGs) are important components of the native extracellular matrix (ECM) able to interact with biological mediator proteins. They can be chemically functionalized and thereby modified in their interaction profiles. Thus, they are promising candidates for functional biomaterials to control healing processes in particular in health-compromised patients. Biophysical studies show that the interaction profiles between mediator proteins and GAGs are strongly influenced by (i) sulphation degree, (ii) sulphation pattern, and (iii) composition and structure of the carbohydrate backbone. Hyaluronan derivatives demonstrate a higher binding strength in their interaction with biological mediators than chondroitin sulphate for a comparable sulphation degree. Furthermore sulphated GAG derivatives alter the interaction profile of mediator proteins with their cell receptors or solute native interaction partners. These results are in line with biological effects on cells relevant for wound healing processes. This is valid for solute GAGs as well as those incorporated in collagen-based artificial ECM (aECMs). Prominent effects are (i) anti-inflammatory, immunomodulatory properties towards macrophages/dendritic cells, (ii) enhanced osteogenic differentiation of human mesenchymal stromal cells, (iii) altered differentiation of fibroblasts to myofibroblasts, (iv) reduced osteoclast activity and (v) improved osseointegration of dental implants in minipigs. The findings of our consortium Transregio 67 contribute to an improved understanding of structure-function relationships of GAG derivatives in their interaction with mediator proteins and cells. This will enable the design of bioinspired, functional biomaterials to selectively control and promote bone and skin regeneration.

Artificial matrices with high-sulfated glycosaminoglycans and collagen are anti-inflammatory and pro-osteogenic for human mesenchymal stromal cells.

Bone healing has been described to be most efficient if the early inflammatory phase is resolved timely. When the inflammation elevates or is permanently established, bone healing becomes impaired and, moreover, bone destruction often takes place. Systemic disorders such as diabetes and bone diseases like arthritis and osteoporosis are associated with sustained inflammation and delayed bone healing. One goal of biomaterial research is the development of materials/surface modifications which support the healing process by inhibiting the inflammatory bone erosion and suppressing pro-inflammatory mediators and by that promoting the bone repair process. In the present study, the influence of artificial extracellular matrices (aECM) on the interleukin (IL)-1ß-induced pro-inflammatory response of human mesenchymal stromal cells (hMSC) was studied. hMSC cultured on aECM composed of collagen I and high-sulfated glycosaminoglycan (GAG) derivatives did not secrete IL-6, IL-8, monocyte chemoattractant protein-1, and prostaglandin E2 in response to IL-1ß. The activation and nuclear translocation of nuclear factor κBp65 induced by IL-1ß, tumor necrosis factor-α or lipopolysaccharide was abrogated. Furthermore, these aECM promoted the osteogenic differentiation of hMSC as determined by an increased activity of tissue non-specific alkaline phosphatase (TNAP); however, the aECM had no effect on the IL-1ß-induced TNAP activity. These data suggest that aECM with high-sulfated GAG derivatives suppress the formation of pro-inflammatory mediators and simultaneously promote the osteogenic differentiation of hMSC. Therefore, these aECM might offer an interesting approach as material/surface modification supporting the bone healing process.

Sulfated glycosaminoglycans support osteoblast functions and concurrently suppress osteoclasts.

In order to improve bone regeneration, development and evaluation of new adaptive biomaterials is warranted. Glycosaminoglycans (GAGs) such as hyaluronan (HA) and chondroitin sulfate (CS) are major extracellular matrix (ECM) components of bone, and display osteogenic properties that are potentially useful for biomaterial applications. Using native and synthetic sulfate-modified GAGs, we manufactured artificial collagen/GAG ECM (aECMs) coatings, and evaluated how the presence of GAGs and their degree of sulfation affects the differentiation of murine mesenchymal stem cells to osteoblasts (OB) cultivated on these aECMs. GAG sulfation regulated osteogenesis at all key steps of OB development. Adhesion, but not migration, was diminished by 50% (P < 0.001). Proliferation and metabolic activity were slightly (P < 0.05) and cell death events strongly (P < 0.001) down-regulated due to a switch from proliferative to matrix synthesis state. When exposed to sulfated GAGs, OB marker genes, such as alkaline phosphatase, osteoprotegerin (OPG), and osteocalcin increased by up to 28-fold (P < 0.05) and calcium deposition up to 4-fold (P < 0.05). Furthermore, GAG treatment of OBs suppressed their ability to support osteoclast (OC) differentiation and resorption. In conclusion, GAG sulfation controls bone cell homeostasis by concurrently promoting osteogenesis and suppressing their paracrine support of OC functions, thus displaying a favorable profile on bone remodeling. Whether these cellular properties translate into improved bone regeneration needs to be validated in vivo.

Sulfated glycosaminoglycans exploit the conformational plasticity of bone morphogenetic protein-2 (BMP-2) and alter the interaction profile with its receptor.

Sulfated glycosaminoglycans (GAGs) can direct cellular processes by interacting with proteins of the extracellular matrix (ECM). In this study we characterize the interaction profiles of chemically sulfated hyaluronan (HA) and chondroitin sulfate (CS) derivatives with bone morphogenetic protein-2 (BMP-2) and investigate their relevance for complex formation with the receptor BMPR-IA. These goals were addressed by surface plasmon resonance (SPR) and ELISA in combination with molecular modeling and dynamics simulation. We found not only the interaction of BMP-2 with GAGs to be dependent on the type and sulfation of GAGs but also BMP-2/GAG/BMPR-IA complex formation. The conformational plasticity of the BMP-2 N-termini plays a key role in the structural and thermodynamic characteristics of the BMP-2/GAG/BMPR-IA system. Hence we propose a model that provides direct insights into the importance of the structural and dynamical properties of the BMP-2/BMPR-IA system for its regulation by sulfated GAGs, in which structural asymmetry plays a key role.

Coating with artificial matrices from collagen and sulfated hyaluronan influences the osseointegration of dental implants.

Dental implants are an established therapy for oral rehabilitation. High success rates are achieved in healthy bone, however, these rates decrease in compromised host bone. Coating of dental implants with components of the extracellular matrix is a promising approach to enhance osseointegration in compromised peri-implant bone. Dental titanium implants were coated with an artificial extracellular matrix (aECM) consisting of collagen type I and either one of two regioselectively low sulfated hyaluronan (sHA) derivatives (coll/sHA1Δ6s and coll/sHA1) and compared to commercial pure titanium implants (control). After extraction of the premolar teeth, 36 implants were inserted into the maxilla of 6 miniature pigs (6 implants per maxilla). The healing periods were 4 and 8 weeks, respectively. After animal sacrifice, the samples were evaluated histomorphologically and histomorphometrically. All surface states led to a sufficient implant osseointegration after 4 and 8 weeks. Inflammatory or foreign body reactions could not be observed. After 4 weeks of healing, implants coated with coll/sHA1Δ6s showed the highest bone implant contact (BIC; coll/sHA1Δ6s: 45.4%; coll/sHA1: 42.2%; control: 42.3%). After 8 weeks, a decrease of BIC could be observed for coll/sHA1Δ6s and controls (coll/sHA1Δ6s: 37.3%; control: 31.7 %). For implants coated with coll/sHA1, the bone implant contact increased (coll/sHA1: 50.8%). Statistically significant differences could not be observed. Within the limits of the current study, aECM coatings containing low sHA increase peri-implant bone formation around dental implants in maxillary bone compared to controls in the early healing period.

Cellular response of advanced triple cultures of human osteocytes, osteoblasts and osteoclasts to high sulfated hyaluronan (sHA3).

Bone remodelling, important for homeostasis and regeneration involves the controlled action of osteoblasts, osteocytes and osteoclasts. The present study established a three-dimensional human in vitro bone model as triple culture with simultaneously differentiating osteocytes and osteoclasts, in the presence of osteoblasts. Since high sulfated hyaluronan (sHA3) was reported as a biomaterial to enhance osteogenesis as well as to dampen osteoclastogenesis, the triple culture was exposed to sHA3 to investigate cellular responses compared to the respective bone cell monocultures. Osteoclast formation and marker expression was stimulated by sHA3 only in triple culture. Osteoprotegerin (OPG) gene expression and protein secretion, but not receptor activator of NF-κB ligand (RANKL) or sclerostin (SOST), were strongly enhanced, suggesting an important role of sHA3 itself in osteoclastogenesis with other targets than indirect modulation of the RANKL/OPG ratio. Furthermore, sHA3 upregulated osteocalcin (BGLAP) in osteocytes and osteoblasts in triple culture, while alkaline phosphatase (ALP) was downregulated.

Sulfated hyaluronan containing collagen matrices enhance cell-matrix-interaction, endocytosis, and osteogenic differentiation of human mesenchymal stromal cells.

Inorganic-organic composite implant materials mimicking the environment of bone are promising applications to meet the increasing demands on biomaterials for bone regeneration caused by extended life spans and the concomitant increase of bone treatments. Besides collagen type I (Col-I) glycosaminoglycans (GAG), such as hyaluronan, are important components of the bone extracellular matrix (ECM). Sulfated GAGs are potential stimulators of bone anabolic activity, as they are involved in the recruitment of mesenchymal stromal cells (MSCs) to the site of bone formation and support differentiation to osteoblasts. Nevertheless, no consecutive data is currently available about the interaction of hyaluronan or sulfated hyaluronan derivatives with hMSCs and the molecular processes being consequently regulated. We applied quantitative proteomics to investigate the influence of artificial ECM composed of Col-I and hyaluronan (Hya) or sulfated hyaluronan (HyaS3) on the molecular adaptation of osteogenic-differentiated human MSCs (hMSCs). Of the 1,370 quantified proteins, the expression of 4-11% was altered due to both aECM-combinations. Our results indicate that HyaS3 enhanced multiple cell functions, including cell-matrix-interaction, cell-signaling, endocytosis, and differentiation. In conclusion, this study provides fundamental insights into regulative cellular responses associated with HyaS3 and Hya as components of aECM and underlines the potential of HyaS3 as a promising implant-coating-material.

Effects of Gamma Irradiation and Supercritical Carbon Dioxide Sterilization on Methacrylated Gelatin/Hyaluronan Hydrogels.

Biopolymer hydrogels have become an important group of biomaterials in experimental and clinical use. However, unlike metallic or mineral materials, they are quite sensitive to sterilization. The aim of this study was to compare the effects of gamma irradiation and supercritical carbon dioxide (scCO2) treatment on the physicochemical properties of different hyaluronan (HA)- and/or gelatin (GEL)-based hydrogels and the cellular response of human bone marrow-derived mesenchymal stem cells (hBMSC). Hydrogels were photo-polymerized from methacrylated HA, methacrylated GEL, or a mixture of GEL/HA. The composition and sterilization methods altered the dissolution behavior of the biopolymeric hydrogels. There were no significant differences in methacrylated GEL release but increased methacrylated HA degradation of gamma-irradiated samples. Pore size/form remained unchanged, while gamma irradiation decreased the elastic modulus from about 29 kPa to 19 kPa compared to aseptic samples. HBMSC proliferated and increased alkaline phosphatase activity (ALP) particularly in aseptic and gamma-irradiated methacrylated GEL/HA hydrogels alike, while scCO2 treatment had a negative effect on both proliferation and osteogenic differentiation. Thus, gamma-irradiated methacrylated GEL/HA hydrogels are a promising base for multi-component bone substitute materials.

Cellular adhesion and chondrogenic differentiation inside an alginate-based bioink in response to tailorable artificial matrices and tannic acid treatment.

Many established bioinks fulfill important requirements regarding fabrication standards and cytocompatibility. Current research focuses on development of functionalized bioinks with an improved support of tissue-specific cell differentiation. Many approaches primarily depend on decellularized extracellular matrices or blood components. In this study, we investigated the combination of a highly viscous alginate-methylcellulose (algMC) bioink with collagen-based artificial extracellular matrix (aECM) as a finely controllable and tailorable system composed of collagen type I (col) with and without chondroitin sulfate (CS) or sulfated hyaluronan (sHA). As an additional stabilizer, the polyphenol tannic acid (TA) was integrated into the inks. The assessment of rheological properties and printability as well as hydrogel microstructure revealed no adverse effect of the integrated components on the inks. Viability, adhesion, and proliferation of bioprinted immortalized human mesenchymal stem cells (hTERT-MSC) was improved indicating enhanced interaction with the designed microenvironment. Furthermore, chondrogenic matrix production (collagen type II and sulfated glycosaminoglycans) by primary human chondrocytes (hChon) was enhanced by aECM. Supplementing the inks with TA was required for these positive effects but caused cytotoxicity as soon as TA concentrations exceeded a certain amount. Thus, combining tailorable aECM with algMC and balanced TA addition proved to be a promising approach for promoting adhesion of immortalized stem cells and differentiation of chondrocytes in bioprinted scaffolds.

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.