Left bundle branch block-induced dilated cardiomyopathy: Definitions, pathophysiology, and therapy.

Left bundle branch block (LBBB) is a frequent finding in patients with heart failure (HF), particularly in those with dilated cardiomyopathy (DCM). LBBB has been commonly described as a consequence of DCM development. However, a total recovery of left ventricular (LV) function after cardiac resynchronization therapy (CRT), observed in patients with LBBB and DCM, has led to increasing acknowledgement of LBBB-induced dilated cardiomyopathy (LBBB-iDCM) as a specific pathological entity. Its recognition has important clinical implications, as LBBB-iDCM patients may benefit from an early CRT strategy rather than medical HF therapy only. At present, there are no definitive diagnostic criteria enabling the universal identification of LBBB-iDCM, and no defined therapeutic approach in this subgroup of patients. This review compiles the main findings about LBBB-iDCM pathophysiology and the current proposed diagnostic criteria and therapeutic approach.

Ancestral aneuploidy and stable chromosomal duplication resulting in differential genome structure and gene expression control in trypanosomatid parasites.

Aneuploidy is widely observed in both unicellular and multicellular eukaryotes, usually associated with adaptation to stress conditions. Chromosomal duplication stability is a tradeoff between the fitness cost of having unbalanced gene copies and the potential fitness gained from increased dosage of specific advantageous genes. Trypanosomatids, a family of protozoans that include species that cause neglected tropical diseases, are a relevant group to study aneuploidies. Their life cycle has several stressors that could select for different patterns of chromosomal duplications and/or losses, and their nearly universal use of polycistronic transcription increases their reliance on gene expansion/contraction, as well as post-transcriptional control as mechanisms for gene expression regulation. By evaluating the data from 866 isolates covering seven trypanosomatid genera, we have revealed that aneuploidy tolerance is an ancestral characteristic of trypanosomatids but has a reduced occurrence in a specific monophyletic clade that has undergone large genomic reorganization and chromosomal fusions. We have also identified an ancient chromosomal duplication that was maintained across these parasite's speciation, named collectively as the trypanosomatid ancestral supernumerary chromosome (TASC). TASC has most genes in the same coding strand, is expressed as a disomic chromosome (even having four copies), and has increased potential for functional variation, but it purges highly deleterious mutations more efficiently than other chromosomes. The evidence of stringent control over gene expression in this chromosome suggests that these parasites have adapted to mitigate the fitness cost associated with this ancient chromosomal duplication.

Descriptive analysis of injury types and incidence during futsal preseason across different competitive levels.

Introduction: This study aimed to verify the typology and incidence of injury by comparing the different competitive levels of futsal during the preseason. Methods: The sample consisted of 68 senior male futsal players (24.26 ± 4.63 years). Data were collected using an injury recording grid that examined the affected body part, anatomical region, type of injury, mechanism, and severity. Results: It was found that the elite group has the lowest incidence rate of injury (4.8 injuries per 1,000 h of exposure) compared to the sub-elite (11.8 injuries per 1,000 h of exposure) and amateur groups (13.9 injuries per 1,000 h of exposure). However, at this level, there is the highest percentage of injury occurrence (38.5%), the lower limb was the most affected part of the body (30.8%), and ligament (23.1%) and muscle (15.4%) injuries are the most prevalent. The most frequent mechanism of injury was non-traumatic (30.8%), and the majority were moderate injuries in the elite (23.1%) and sub-elite (17.9%) groups and severe injuries in the amateur group (12.5%). Discussion: The amateur futsal players had the highest incidence of injury during the preseason period compared to the other competitive levels. Still, it was at the elite level where the highest percentage of injuries occurred, most of them non-traumatic and of ligament origin, primarily affecting the ankle region. The results highlight the importance of adopting specific injury prevention programs for ligament and muscle injuries during the preseason phase, regardless of the competitive level.

In vivo assessment of marine vs bovine origin collagen-based composite scaffolds promoting bone regeneration in a New Zealand rabbit model.

The ability of human tissues to self-repair is limited, which motivates the scientific community to explore new and better therapeutic approaches to tissue regeneration. The present manuscript provides a comparative study between a marine-based composite biomaterial, and another composed of well-established counterparts for bone tissue regeneration. Blue shark skin collagen was combined with bioapatite obtained from blue shark's teeth (mColl:BAp), while bovine collagen was combined with synthetic hydroxyapatite (bColl:Ap) to produce 3D composite scaffolds by freeze-drying. Collagens showed similar profiles, while apatite particles differed in their composition, being the marine bioapatite a fluoride-enriched ceramic. The marine-sourced biomaterials presented higher porosities, improved mechanical properties, and slower degradation rates when compared to synthetic apatite-reinforced bovine collagen. The in vivo performance regarding bone tissue regeneration was evaluated in defects created in femoral condyles in New Zealand rabbits twelve weeks post-surgery. Micro-CT results showed that mColl:BAp implanted condyles had a slower degradation and an higher tissue formation (17.9 ± 6.9 %) when compared with bColl:Ap implanted ones (12.9 ± 7.6 %). The histomorphometry analysis provided supporting evidence, confirming the observed trend by quantifying 13.1 ± 7.9 % of new tissue formation for mColl:BAp composites and 10.4 ± 3.2 % for bColl:Ap composites, suggesting the potential use of marine biomaterials for bone regeneration.

The Characterization and Cytotoxic Evaluation of Chondrosia reniformis Collagen Isolated from Different Body Parts (Ectosome and Choanosome) Envisaging the Development of Biomaterials.

Chondrosia reniformis is a collagen-rich marine sponge that is considered a sustainable and viable option for producing an alternative to mammalian-origin collagens. However, there is a lack of knowledge regarding the properties of collagen isolated from different sponge parts, namely the outer region, or cortex, (ectosome) and the inner region (choanosome), and how it affects the development of biomaterials. In this study, a brief histological analysis focusing on C. reniformis collagen spatial distribution and a comprehensive comparative analysis between collagen isolated from ectosome and choanosome are presented. The isolated collagen characterization was based on isolation yield, Fourier-transformed infrared spectroscopy (FTIR), circular dichroism (CD), SDS-PAGE, dot blot, and amino acid composition, as well as their cytocompatibility envisaging the development of future biomedical applications. An isolation yield of approximately 20% was similar for both sponge parts, as well as the FTIR, CD, and SDS-PAGE profiles, which demonstrated that both isolated collagens presented a high purity degree and preserved their triple helix and fibrillar conformation. Ectosome collagen had a higher OHpro content and possessed collagen type I and IV, while the choanosome was predominately constituted by collagen type IV. In vitro cytotoxicity assays using the L929 fibroblast cell line displayed a significant cytotoxic effect of choanosome collagen at 2 mg/mL, while ectosome collagen enhanced cell metabolism and proliferation, thus indicating the latter as being more suitable for the development of biomaterials. This research represents a unique comparative study of C. reniformis body parts, serving as a support for further establishing this marine sponge as a promising alternative collagen source for the future development of biomedical applications.

Authors' Response.

Dear Editor, We would like to thank Dr. Madias for his valuable comment on our original article entitled "QT interval prolongation in Takotsubo Syndrome: a frightening feature with no major prognostic impact" published in Monaldi Archives for Chest Disease on December 6, 2023...

Secretome processing for proteomics: A methods comparison.

The cancer cell secretome comprises a treasure-trove for biomarkers since it reflects cross-talk between tumor cells and their surrounding environment with high detectability in biofluids. In this study, we evaluated six secretome sample processing workflows coupled to single-shot mass spectrometry: (1) Protein concentration by ultrafiltration with a molecular weight cut-off (MWCO) filter and sample preparation through in-gel digestion (IGD); (2) Acetone protein precipitation coupled to IGD; (3) MWCO filter-based protein concentration followed by to in-solution digestion (ISD); (4) Acetone protein precipitation coupled to ISD; (5) Direct ISD; (6) Secretome lyophilization and ISD. To this end, we assessed workflow triplicates in terms of total number of protein identifications, unique identifications, reproducibility of protein identification and quantification and detectability of small proteins with important functions in cancer biology such as cytokines, chemokines, and growth factors. Our findings revealed that acetone protein precipitation coupled to ISD outperformed the other methods in terms of the number of identified proteins (2246) and method reproducibility (correlation coefficient between replicates (r = 0.94, CV = 19%). Overall, especially small proteins such as those from the classes mentioned above were better identified using ISD workflows. Concluding, herein we report that secretome protein precipitation coupled to ISD is the method of choice for high-throughput secretome proteomics via single shot nanoLC-MS/MS.

3D bioactive ionic liquid-based architectures: An anti-inflammatory approach for early-stage osteoarthritis.

3D bioprinting enables the fabrication of biomimetic cell-laden constructs for cartilage regeneration, offering exclusive strategies for precise pharmacological screenings in osteoarthritis (OA). Synovial inflammation plays a crucial role in OA's early stage and progression, characterized by the increased of the synovial pro-inflammatory mediators and cytokines and chondrocyte apoptosis. Therefore, there is an urgent need to develop solutions for effectively managing the primary events associated with OA. To address these issues, a phenolic-based biocompatible ionic liquid approach, combining alginate (ALG), acemannan (ACE), and cholinium caffeate (Ch[Caffeate]), was used to produce easily printable bioinks. Through the use of this strategy 3D constructs with good printing resolution and high structural integrity were obtained. The encapsulation of chondrocytes like ATDC5 cells provided structures with good cell distribution, viability, and growth, for up to 14 days. The co-culture of the constructs with THP-1 macrophages proved their ability to block pro-inflammatory cytokines (TNF-α and IL-6) and mediators (GM-CSF), released by the cultured cells. Moreover, incorporating the biocompatible ionic liquid into the system significantly improved its bioactive performance without compromising its physicochemical features. These findings demonstrate that ALG/ACE/Ch[Caffeate] bioinks have great potential for bioengineering cartilage tissue analogs. Besides, the developed ALG/ACE/Ch[Caffeate] bioinks protected encapsulated chondrocyte-like cells from the effect of the inflammation, assessed by a co-culture system with THP-1 macrophages. These results support the increasing use of Bio-ILs in the biomedical field, particularly for developing 3D bioprinting-based constructs to manage inflammatory-based changes in OA. STATEMENT OF SIGNIFICANCE: Combining natural resources with active biocompatible ionic liquids (Bio-IL) for 3D printing is herein presented as an approach for the development of tools to manage inflammatory osteoarthritis (OA). We propose combining alginate (ALG), acemannan (ACE), and cholinium caffeate (Ch[Caffeate]), a phenolic-based Bio-IL with anti-inflammatory and antioxidant features, to produce bioinks that allow to obtain 3D constructs with good printing resolution, structural integrity, and that provide encapsulated chondrocyte-like cells good viability. The establishment of a co-culture system using the printed constructs and THP-1-activated macrophages allowed us to study the encapsulated chondrocyte-like cells behaviour within an inflammatory scenario, a typical event in early-stage OA. The obtained outcomes support the beneficial use of Bio-ILs in the biomedical field, particularly for the development of 3D bioprinting-based models that allow the monitoring of inflammatory-based events in OA.

QT interval prolongation in Takotsubo syndrome: a frightening feature with no major prognostic impact.

Despite the frequent and often severe repolarization abnormalities seen in Takotsubo syndrome (TTS), the underlying mechanism of life-threatening arrhythmias is incompletely understood, and the risk remains uncertain. TTS is considered a potential cause of acquired long QT syndrome; however, there is no robust evidence that QT prolongation has a major prognostic impact on these patients' outcomes. Our aim was to assess the prevalence and clinical implications of acquired long QT during TTS events and compare in-hospital and long-term outcomes between patients with and without corrected QT interval (QTc) prolongation. This is a retrospective cohort study that included 113 patients admitted to our tertiary care hospital with a diagnosis of TTS. The cohort was divided into two groups: a long QTc group (QTc≥460 milliseconds in any electrocardiogram at admission or during hospitalization) and a normal QTc group. Baseline characteristics, occurrences during hospitalization, and outcome data were obtained from the revision of medical registries and hospital visits. Of the 113 patients, 107 (94.7%) were female. The mean age was 67.6±11.7 years. QTc prolongation was found in 38%. Demographic characteristics, relevant chronic medication, prevalence of cardiovascular risk factors, and other comorbidities were similar between the groups, except for history of atrial fibrillation, which was more common in the long QTc group. Syncope was more prevalent in the long QTc group. In-hospital complications were not statistically different between patients with long and normal QTc (48.8% versus 44.2%, p=0.637), including ventricular arrhythmias and complete atrioventricular block (both 4.7% versus 1.4%, p=0.556). In-hospital mortality was 0.9%, corresponding to one patient in the long QTc group. The mean follow-up time was 4.8±3.8 years. 5-year all-cause mortality and the occurrence of the composite endpoint of major adverse cardiac and cerebrovascular events did not differ between the groups (p=0.511 and p=0.538, respectively). Our study found no association between prolonged QTc interval during TTS events and adverse prognosis, since in-hospital and long-term outcomes were similar between the groups. Our findings suggest that, although QT prolongation is usually a frightening feature on ECG, this repolarization abnormality during the acute phase has no major prognostic implications in the TTS population.

An allele-selective inter-chromosomal protein bridge supports monogenic antigen expression in the African trypanosome.

UPF1-like helicases play roles in telomeric heterochromatin formation and X-chromosome inactivation, and also in monogenic variant surface glycoprotein (VSG) expression via VSG exclusion-factor-2 (VEX2), a UPF1-related protein in the African trypanosome. We show that VEX2 associates with chromatin specifically at the single active VSG expression site on chromosome 6, forming an allele-selective connection, via VEX1, to the trans-splicing locus on chromosome 9, physically bridging two chromosomes and the VSG transcription and splicing compartments. We further show that the VEX-complex is multimeric and self-regulates turnover to tightly control its abundance. Using single cell transcriptomics following VEX2-depletion, we observed simultaneous derepression of many other telomeric VSGs and multi-allelic VSG expression in individual cells. Thus, an allele-selective, inter-chromosomal, and self-limiting VEX1-2 bridge supports monogenic VSG expression and multi-allelic VSG exclusion.

RAD51-mediated R-loop formation acts to repair transcription-associated DNA breaks driving antigenic variation in Trypanosoma brucei.

RNA-DNA hybrids are epigenetic features of all genomes that intersect with many processes, including transcription, telomere homeostasis, and centromere function. Increasing evidence suggests that RNA-DNA hybrids can provide two conflicting roles in the maintenance and transmission of genomes: They can be the triggers of DNA damage, leading to genome change, or can aid the DNA repair processes needed to respond to DNA lesions. Evasion of host immunity by African trypanosomes, such as Trypanosoma brucei, relies on targeted recombination of silent Variant Surface Glycoprotein (VSG) genes into a specialized telomeric locus that directs transcription of just one VSG from thousands. How such VSG recombination is targeted and initiated is unclear. Here, we show that a key enzyme of T. brucei homologous recombination, RAD51, interacts with RNA-DNA hybrids. In addition, we show that RNA-DNA hybrids display a genome-wide colocalization with DNA breaks and that this relationship is impaired by mutation of RAD51. Finally, we show that RAD51 acts to repair highly abundant, localised DNA breaks at the single transcribed VSG and that mutation of RAD51 alters RNA-DNA hybrid abundance at 70 bp repeats both around the transcribed VSG and across the silent VSG archive. This work reveals a widespread, generalised role for RNA-DNA hybrids in directing RAD51 activity during recombination and uncovers a specialised application of this interplay during targeted DNA break repair needed for the critical T. brucei immune evasion reaction of antigenic variation.

Immunoprecipitation of RNA-DNA hybrid interacting proteins in Trypanosoma brucei reveals conserved and novel activities, including in the control of surface antigen expression needed for immune evasion by antigenic variation.

RNA-DNA hybrids are epigenetic features of genomes that provide a diverse and growing range of activities. Understanding of these functions has been informed by characterising the proteins that interact with the hybrids, but all such analyses have so far focused on mammals, meaning it is unclear if a similar spectrum of RNA-DNA hybrid interactors is found in other eukaryotes. The African trypanosome is a single-cell eukaryotic parasite of the Discoba grouping and displays substantial divergence in several aspects of core biology from its mammalian host. Here, we show that DNA-RNA hybrid immunoprecipitation coupled with mass spectrometry recovers 602 putative interactors in T. brucei mammal- and insect-infective cells, some providing activities also found in mammals and some lineage-specific. We demonstrate that loss of three factors, two putative helicases and a RAD51 paralogue, alters T. brucei nuclear RNA-DNA hybrid and DNA damage levels. Moreover, loss of each factor affects the operation of the parasite immune survival mechanism of antigenic variation. Thus, our work reveals the broad range of activities contributed by RNA-DNA hybrids to T. brucei biology, including new functions in host immune evasion as well as activities likely fundamental to eukaryotic genome function.

Treatment of salt from hides curing stage by electrocoagulation for use in the pickling stage of the tanning industry.

The raw materials for the tanning industry, namely hides and skins, are preserved (curing stage) and carried with common salt, i.e., sodium chloride (NaCl). Proceeding to conversion into leather, pickling is a key stage of the tannery process, which entails high demand of water and salt. In this work, the salt-derived brine (SdB) generated from the curing of hides was treated by iron-driven electrocoagulation (EC), aiming at its later application in the pickling stage of the tanning industry, promoting a transition to zero waste emission policy. Focusing on reducing the brine's total organic carbon (TOC), central composite rotational design and response surface methodology were adopted to study the effect of electrolysis time (6.2-14.2 min) and current density (74-431 A·m-2) on the treatment of the SdB (≅ 7.5 % wt. NaCl). The quality of the treated brines was then assessed in pickling trials and compared with virgin brine. 68-83 % removal of TOC from the SdB were achieved under electrolysis time ranging 6.2-14.2 min and current density ranging 126-252 A·m-2. Under these operating ranges the quality of the wet-blue leathers was guaranteed. Lowest power consumption (0.44 kWh·m-3) was achieved under electrolysis time of 6 min and current density of 126 A·m-2, yielding 68 % removal of TOC. Moreover, the shrinkage temperature of the hides was improved with treated brine (103.5 °C-110.5 °C) compared to virgin brine (103.0 °C). The present study provides strong evidence that contaminated salt from the curing stage can be valorised within the tanning industry through electrocoagulation treatment and then used in another production stage, instead of being landfilled.

In Vitro Antiprotozoal Activity of Hibiscus sabdariffa Extract against a Ciliate Causing High Mortalities in Turbot Aquaculture.

Philasterides dicentrarchi is an histophagous parasite that infects flatfish, namely turbot (Scophthalmus maximus), and cause significant losses in aquaculture units. The available measures for P. dicentrarchi control have limited efficiency, and some cause harm to fish. Hence, sustainable and natural control strategies are urgently needed. This study evaluated the in vitro bioactivity of the ethanol extract of Hibiscus sabdariffa calyces on P. dicentrarchi population growth rate (PGR), oxidative stress biomarkers (glutathione-S-transferases (GST), glutathione reductase (GR), glutathione peroxidase (GPx), total glutathione (TG) and catalase (CAT), neurotoxicity (acetylcholinesterase, AChE), activity and gene expression of proteases as major virulence factors. H. sabdariffa extract inhibited parasite PGR (IC50 = 1.57 mg mL-1), and caused significant changes in the activity of antioxidant enzymes (LOEC = 0.22 mg mL-1), especially GPx, TG, and CAT. The activity of proteases was also severely inhibited (IC50 = 0.76 mg mL-1), and gene expression of catepsin 90 and leishmanolysin proteases was downregulated. Organic acids and phenolic phytochemicals in hibiscus extract are potentially responsible for the antiprotozoal bioactivity herein determined. Therefore, H. sabdariffa extract can be a promising disease-control alternative against the ciliate proliferation, cellular defense mechanisms and pathogenicity. Still, its applicability in aquaculture settings, and potential effects on farmed fish, should be further elucidated.

Profiling the bloodstream form and procyclic form Trypanosoma brucei cell cycle using single-cell transcriptomics.

African trypanosomes proliferate as bloodstream forms (BSFs) and procyclic forms in the mammal and tsetse fly midgut, respectively. This allows them to colonise the host environment upon infection and ensure life cycle progression. Yet, understanding of the mechanisms that regulate and drive the cell replication cycle of these forms is limited. Using single-cell transcriptomics on unsynchronised cell populations, we have obtained high resolution cell cycle regulated (CCR) transcriptomes of both procyclic and slender BSF Trypanosoma brucei without prior cell sorting or synchronisation. Additionally, we describe an efficient freeze-thawing protocol that allows single-cell transcriptomic analysis of cryopreserved T. brucei. Computational reconstruction of the cell cycle using periodic pseudotime inference allowed the dynamic expression patterns of cycling genes to be profiled for both life cycle forms. Comparative analyses identify a core cycling transcriptome highly conserved between forms, as well as several genes where transcript levels dynamics are form specific. Comparing transcript expression patterns with protein abundance revealed that the majority of genes with periodic cycling transcript and protein levels exhibit a relative delay between peak transcript and protein expression. This work reveals novel detail of the CCR transcriptomes of both forms, which are available for further interrogation via an interactive webtool.

Syndecan-4 is a maestro of gastric cancer cell invasion and communication that underscores poor survival.

Gastric cancer is a dominating cause of cancer-associated mortality with limited therapeutic options. Here, we show that syndecan-4 (SDC4), a transmembrane proteoglycan, is highly expressed in intestinal subtype gastric tumors and that this signature associates with patient poor survival. Further, we mechanistically demonstrate that SDC4 is a master regulator of gastric cancer cell motility and invasion. We also find that SDC4 decorated with heparan sulfate is efficiently sorted in extracellular vesicles (EVs). Interestingly, SDC4 in EVs regulates gastric cancer cell-derived EV organ distribution, uptake, and functional effects in recipient cells. Specifically, we show that SDC4 knockout disrupts the tropism of EVs for the common gastric cancer metastatic sites. Our findings set the basis for the molecular implications of SDC4 expression in gastric cancer cells and provide broader perspectives on the development of therapeutic strategies targeting the glycan-EV axis to limit tumor progression.

The world upside down - after 20 years of follow-up of dextro-transposition of the great arteries.

Dextro-transposition of the great arteries (D-TGA) is a congenital heart disease (CHD) classically palliated with atrial switch (ATR-S) and nowadays corrected with arterial switch (ART-S). Our aim was to observe a group of D-TGA patients followed in an adult CHD Outpatient Clinic. We analyzed a group of D-TGA patients born between 1974 and 2001. Adverse events were defined as a composite of death, stroke, myocardial infarction or coronary revascularization, arrhythmia, and ventricular, baffle or significative valvular dysfunction. A total of 79 patients were enrolled, 46% female, mean follow-up of 27±6 years after surgery. ATR-S was performed in 54% and ART-S in 46%; median age at procedure was 13 months and 10 days, respectively. During follow-up, almost all ART-S remained in sinus rhythm versus 64% of ATR-S (p=0.002). The latter group had a higher incidence of arrhythmias (41% versus 3%, p<0.001), mostly atrial flutter or fibrillation; median time to first arrhythmia was 23 years. Systemic ventricle systolic dysfunction (SVSD) was more frequent in ATR-S (41% versus 0%, p<0.001); mean time to SVSD was 25 years. In ART-S, the most frequent complication was significant valvular regurgitation (14%). Regarding time-to-event analysis, 80% and 40% of ATR-S maintained adverse-events-free after 20 and 30 years, respectively; the time-to-first-adverse-event was 23 years and there was no difference compared to ART-S (Log-rank=0.596). ART-S tended to maintain more preserved biventricular function than ATR-S (Log-rank=0.055). After a long-term free of adverse events, ATR-S patients experienced more arrhythmias and SVSD. ART-S complications were predominantly anastomosis related; SVSD or arrhythmias were rare.

Marine Gelatin-Methacryloyl-Based Hydrogels as Cell Templates for Cartilage Tissue Engineering.

Marine-origin gelatin has been increasingly used as a safe alternative to bovine and porcine ones due to their structural similarity, avoiding the health-related problems and sociocultural concerns associated with using mammalian-origin materials. Another benefit of marine-origin gelatin is that it can be produced from fish processing-products enabling high production at low cost. Recent studies have demonstrated the excellent capacity of gelatin-methacryloyl (GelMA)-based hydrogels in a wide range of biomedical applications due to their suitable biological properties and tunable physical characteristics, such as tissue engineering applications, including the engineering of cartilage. In this study, fish gelatin was obtained from Greenland halibut skins by an acidic extraction method and further functionalized by methacrylation using methacrylic anhydride, developing a photosensitive gelatin-methacryloyl (GelMA) with a degree of functionalization of 58%. The produced marine GelMA allowed the fabrication of photo-crosslinked hydrogels by incorporating a photoinitiator and UV light exposure. To improve the biological performance, GelMA was combined with two glycosaminoglycans (GAGs): hyaluronic acid (HA) and chondroitin sulfate (CS). GAGs methacrylation reaction was necessary, rendering methacrylated HA (HAMA) and methacrylated CS (CSMA). Three different concentrations of GelMA were combined with CSMA and HAMA at different ratios to produce biomechanically stable hydrogels with tunable physicochemical features. The 20% (w/v) GelMA-based hydrogels produced in this work were tested as a matrix for chondrocyte culture for cartilage tissue engineering with formulations containing both HAMA and CSMA showing improved cell viability. The obtained results suggest these hybrid hydrogels be used as promising biomaterials for cartilage tissue engineering applications.