Oxidized Phospholipids Regulate Tenocyte Function via Induction of Amphiregulin in Dendritic Cells.

Inflammation is a driving force of tendinopathy. The oxidation of phospholipids by free radicals is a consequence of inflammatory reactions and is an important indicator of tissue damage. Here, we have studied the impact of oxidized phospholipids (OxPAPC) on the function of human tenocytes. We observed that treatment with OxPAPC did not alter the morphology, growth and capacity to produce collagen in healthy or diseased tenocytes. However, since OxPAPC is a known modulator of the function of immune cells, we analyzed whether OxPAPC-treated immune cells might influence the fate of tenocytes. Co-culture of tenocytes with immature, monocyte-derived dendritic cells treated with OxPAPC (Ox-DCs) was found to enhance the proliferation of tenocytes, particularly those from diseased tendons. Using transcriptional profiling of Ox-DCs, we identified amphiregulin (AREG), a ligand for EGFR, as a possible mediator of this proliferation enhancing effect, which we could confirm using recombinant AREG. Of note, diseased tenocytes were found to express higher levels of EGFR compared to tenocytes isolated from healthy donors and show a stronger proliferative response upon co-culture with Ox-DCs, as well as AREG treatment. In summary, we identify an AREG-EGFR axis as a mediator of a DC-tenocyte crosstalk, leading to increased tenocyte proliferation and possibly tendon regeneration.

Bottom-Up Strategy to Forecast the Drug Location and Release Kinetics in Antitumoral Electrospun Drug Delivery Systems.

Electrospun systems are becoming promising devices usable for topical treatments. They are eligible to deliver different therapies, from anti-inflammatory to antitumoral. In the current research, polycaprolactone electrospun membranes loaded with synthetic and commercial antitumoral active substances were produced, underlining how the matrix-filler affinity is a crucial parameter for designing drug delivery devices. Nanofibrous membranes loaded with different percentages of Dacarbazine (the drug of choice for melanoma) and a synthetic derivative of Dacarbazine were produced and compared to membranes loaded with AuM1, a highly active Au-complex with low affinity to the matrix. AFM morphologies showed that the surface profile of nanofibers loaded with affine substances is similar to one of the unloaded systems, thanks to the nature of the matrix-filler interaction. FTIR analyses proved the efficacy of the interaction between the amidic group of the Dacarbazine and the polycaprolactone. In AuM1-loaded membranes, because of the weak matrix-filler interaction, the complex is mainly aggregated in nanometric domains on the nanofiber surface, which manifests a nanometric roughness. Consequently, the release profiles follow a Fickian behavior for the Dacarbazine-based systems, whereas a two-step with a highly prominent burst effect was observed for AuM1 systems. The performed antitumoral tests evidence the high-cytotoxic activity of the electrospun systems against melanoma cell lines, proving that the synthetic substances are more active than the commercial dacarbazine.

Endotenon-Derived Type II Tendon Stem Cells Have Enhanced Proliferative and Tenogenic Potential.

Tendon injuries caused by overuse or age-related deterioration are frequent. Incomplete knowledge of somatic tendon cell biology and their progenitors has hindered interventions for the effective repair of injured tendons. Here, we sought to compare and contrast distinct tendon-derived cell populations: type I and II tendon stem cells (TSCs) and tenocytes (TNCs). Porcine type I and II TSCs were isolated via the enzymatic digestion of distinct membranes (paratenon and endotenon, respectively), while tenocytes were isolated through an explant method. Resultant cell populations were characterized by morphology, differentiation, molecular, flow cytometry, and immunofluorescence analysis. Cells were isolated, cultured, and evaluated in two alternate oxygen concentrations (physiological (2%) and air (21%)) to determine the role of oxygen in cell biology determination within this relatively avascular tissue. The different cell populations demonstrated distinct proliferative potential, morphology, and transcript levels (both for tenogenic and stem cell markers). In contrast, all tendon-derived cell populations displayed multipotent differentiation potential and immunophenotypes (positive for CD90 and CD44). Type II TSCs emerged as the most promising tendon-derived cell population for expansion, given their enhanced proliferative potential, multipotency, and maintenance of a tenogenic profile at early and late passage. Moreover, in all cases, physoxia promoted the enhanced proliferation and maintenance of a tenogenic profile. These observations help shed light on the biological mechanisms of tendon cells, with the potential to aid in the development of novel therapeutic approaches for tendon disorders.

Activity and Selectivity of Novel Chemical Metallic Complexes with Potential Anticancer Effects on Melanoma Cells.

Human malignant melanoma cells from lymph node metastatic site (MeWo) were selected for testing several synthesized and purified silver(I) and gold(I) complexes stabilized by unsymmetrically substituted N-heterocyclic carbene (NHC) ligands, called L20 (N-methyl, N'-[2-hydroxy ethylphenyl]imidazol-2-ylide) and M1 (4,5-dichloro, N-methyl, N'-[2-hydroxy ethylphenyl]imidazol-2-ylide), having halogenide (Cl- or I-) or aminoacyl (Gly=N-(tert-Butoxycarbonyl)glycinate or Phe=(S)-N-(tert-Butoxycarbonyl)phenylalaninate) counterion. For AgL20, AuL20, AgM1 and AuM1, the Half-Maximal Inhibitory Concentration (IC50) values were measured, and all complexes seemed to reduce cell viability more effectively than Cisplatin, selected as control. The complex named AuM1 was the most active just after 8 h of treatment at 5 µM, identified as effective growth inhibition concentration. AuM1 also showed a linear dose and time-dependent effect. Moreover, AuM1 and AgM1 modified the phosphorylation levels of proteins associated with DNA lesions (H2AX) and cell cycle progression (ERK). Further screening of complex aminoacyl derivatives indicated that the most powerful were those indicated with the acronyms: GlyAg, PheAg, AgL20Gly, AgM1Gly, AuM1Gly, AgL20Phe, AgM1Phe, AuM1Phe. Indeed, the presence of Boc-Glycine (Gly) and Boc-L-Phenylalanine (Phe) showed an improved efficacy of Ag main complexes, as well as that of AuM1 derivatives. Selectivity was further checked on a non-cancerous cell line, a spontaneously transformed aneuploid immortal keratinocyte from adult human skin (HaCaT). In such a case, AuM1 and PheAg complexes resulted as the most selective allowing HaCaT viability at 70 and 40%, respectively, after 48 h of treatment at 5 µM. The same complexes tested on 3D MeWo static culture induced partial spheroid disaggregation after 24 h of culture, with almost half of the cells dead.

Electrospun Membranes Designed for Burst Release of New Gold-Complexes Inducing Apoptosis of Melanoma Cells.

Two non-commercial metallic Au-based complexes were tested against one of the most aggressive malignant melanomas of the skin (MeWo cells), through cell viability and time-lapse live-cell imaging system assays. The tests with the complexes were carried out both in the form of free metallic complexes, directly in contact with the MeWo cell line culture, and embedded in fibers of Polycaprolactone (PCL) membranes produced by the electrospinning technique. Membranes functionalized with complexes were prepared to evaluate the efficiency of the membranes against the melanoma cells and therefore their feasibility in the application as an antitumoral patch for topical use. Both series of tests highlighted a very effective antitumoral activity, manifesting a very relevant cell viability inhibition after both 24 h and 48 h. In the case of the AuM1 complex at the concentration of 20 mM, melanoma cells completely died in this short period of time. A mortality of around 70% was detected from the tests performed using the membranes functionalized with AuM1 complex at a very low concentration (3 wt.%), even after 24 h of the contact period. The synthesized complexes also manifest high selectivity with respect to the MeWo cells. The peculiar structural and morphological organization of the nanofibers constituting the membranes allows for a very effective antitumoral activity in the first 3 h of treatment. Experimental points of the release profiles were perfectly fitted with theoretical curves, which easily allow interpretation of the kinetic phenomena occurring in the release of the synthesized complexes in the chosen medium.

Stem Cell and Macrophage Roles in Skeletal Muscle Regenerative Medicine.

In severe muscle injury, skeletal muscle tissue structure and functionality can be repaired through the involvement of several cell types, such as muscle stem cells, and innate immune responses. However, the exact mechanisms behind muscle tissue regeneration, homeostasis, and plasticity are still under investigation, and the discovery of pathways and cell types involved in muscle repair can open the way for novel therapeutic approaches, such as cell-based therapies involving stem cells and peripheral blood mononucleate cells. Indeed, peripheral cell infusions are a new therapy for muscle healing, likely because autologous peripheral blood infusion at the site of injury might enhance innate immune responses, especially those driven by macrophages. In this review, we summarize current knowledge on functions of stem cells and macrophages in skeletal muscle repairs and their roles as components of a promising cell-based therapies for muscle repair and regeneration.

Dose-Response Tendon-Specific Markers Induction by Growth Differentiation Factor-5 in Human Bone Marrow and Umbilical Cord Mesenchymal Stem Cells.

Mesenchymal stem cells derived from human bone marrow (hBM-MSCs) are utilized in tendon tissue-engineering protocols while extra-embryonic cord-derived, including from Wharton's Jelly (hWJ-MSCs), are emerging as useful alternatives. To explore the tenogenic responsiveness of hBM-MSCs and hWJ-MSCs to human Growth Differentiation Factor 5 (hGDF-5) we supplemented each at doses of 1, 10, and 100 ng/mL of hGDF-5 and determined proliferation, morphology and time-dependent expression of tenogenic markers. We evaluated the expression of collagen types 1 (COL1A1) and 3 (COL3A1), Decorin (DCN), Scleraxis-A (SCX-A), Tenascin-C (TNC) and Tenomodulin (TNMD) noting the earliest and largest increase with 100 ng/mL. With 100 ng/mL, hBM-MSCs showed up-regulation of SCX-A (1.7-fold) at Day 1, TNC (1.3-fold) and TNMD (12-fold) at Day 8. hWJ-MSCs, at the same dose, showed up-regulation of COL1A1 (3-fold), DCN (2.7-fold), SCX-A (3.8-fold) and TNC (2.3-fold) after three days of culture. hWJ-MSCs also showed larger proliferation rate and marked aggregation into a tubular-shaped system at Day 7 (with 100 ng/mL of hGDF-5). Simultaneous to this, we explored the expression of pro-inflammatory (IL-6, TNF, IL-12A, IL-1ß) and anti-inflammatory (IL-10, TGF-ß1) cytokines across for both cell types. hBM-MSCs exhibited a better balance of pro-inflammatory and anti-inflammatory cytokines up-regulating IL-1ß (11-fold) and IL-10 (10-fold) at Day 8; hWJ-MSCs, had a slight expression of IL-12A (1.5-fold), but a greater up-regulation of IL-10 (2.5-fold). Type 1 collagen and tenomodulin proteins, detected by immunofluorescence, confirming the greater protein expression when 100 ng/mL were supplemented. In the same conditions, both cell types showed specific alignment and shape modification with a length/width ratio increase, suggesting their response in activating tenogenic commitment events, and they both potential use in 3D in vitro tissue-engineering protocols.

In Vitro Innovation of Tendon Tissue Engineering Strategies.

Tendinopathy is the term used to refer to tendon disorders. Spontaneous adult tendon healing results in scar tissue formation and fibrosis with suboptimal biomechanical properties, often resulting in poor and painful mobility. The biomechanical properties of the tissue are negatively affected. Adult tendons have a limited natural healing capacity, and often respond poorly to current treatments that frequently are focused on exercise, drug delivery, and surgical procedures. Therefore, it is of great importance to identify key molecular and cellular processes involved in the progression of tendinopathies to develop effective therapeutic strategies and drive the tissue toward regeneration. To treat tendon diseases and support tendon regeneration, cell-based therapy as well as tissue engineering approaches are considered options, though none can yet be considered conclusive in their reproduction of a safe and successful long-term solution for full microarchitecture and biomechanical tissue recovery. In vitro differentiation techniques are not yet fully validated. This review aims to compare different available tendon in vitro differentiation strategies to clarify the state of art regarding the differentiation process.

Liposomes for Intra-Articular Analgesic Drug Delivery in Orthopedics: State-of-Art and Future Perspectives. Insights from a Systematic Mini-Review of the Literature.

Background and objectives: Liposomal structures are artificial vesicles composed of one or several lamellae of phospholipids which surround an inner aqueous core. Given the amphoteric nature of phospholipids, liposomes are promising systems for drug delivery. The present review provides an updated synthesis of the main techniques for the production of liposomes for orthopedic applications, focusing on the drawbacks of the conventional methods and on the advantages of high pressure techniques. Materials and Methods: Articles published in any language were systematically retrieved from two major electronic scholarly databases (PubMed/MEDLINE and Scopus) up to March 2020. Nine articles were retained based on the "Preferred Reporting Items for Systematic Reviews and Meta-Analyses" (PRISMA) guidelines. Results: Liposome vesicles decrease the rate of inflammatory reactions after local injections, and significantly enhance the clinical effectiveness of anti-inflammatory agents providing controlled drug release, reducing toxic side effects. Conclusions: This review presents an update on the improvement in musculoskeletal ailments using liposome treatment.

MicroRNA in osteoarthritis: physiopathology, diagnosis and therapeutic challenge.

BACKGROUND: Osteoarthritis (OA) is the most orthopedic condition. The pattern of gene expression and the transcription factors that exert control of chondrogenesis have been extensively studied. SOURCES OF DATA: A systematic search (up to July 2018) of articles assessing the role of microRNA (miRNA) in physiopathology, diagnosis and therapy of OA was performed, with the purpose of giving a critical perspective of the possibilities for diagnostic and therapeutic use of miRNA in the management of OA. AREAS OF AGREEMENT: miRNAs are small noncoding RNAs that can regulate gene expression in human cells. miRNAs can be expressed in a different fashion in osteoarthritic compared to nonosteoarthritic cartilage. AREAS OF CONTROVERSY: The mechanisms that produce alteration of gene expression in OA are still not completely understood. miRNAs may be involved in the diagnosis of OA as well as in its treatment. GROWING POINTS: There are complex interactions between miRNAs and their multiple target genes. These interactions may be important in gene regulation and the control of homeostatic pathways in OA. AREAS TIMELY FOR DEVELOPING RESEARCH: miRNA could be useful for diagnostic or management purposes, but the issue of delivery of miRNA targeting agents needs to be overcome before miRNA can be applied in clinical practice.

Biomechanical issues of tissue-engineered constructs for articular cartilage regeneration: in vitro and in vivo approaches.

BACKGROUND: Given the limited regenerative capacity of injured articular cartilage, the absence of suitable therapeutic options has encouraged tissue-engineering approaches for its regeneration or replacement. SOURCES OF DATA: Published articles in any language identified in PubMed and Scopus electronic databases up to August 2019 about the in vitro and in vivo properties of cartilage engineered constructs. A total of 64 articles were included following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. AREAS OF AGREEMENT: Regenerated cartilage lacks the biomechanical and biological properties of native articular cartilage. AREAS OF CONTROVERSY: There are many different approaches about the development of the architecture and the composition of the scaffolds. GROWING POINTS: Novel tissue engineering strategies focus on the development of cartilaginous biomimetic materials able to repair cartilage lesions in association to cell, trophic factors and gene therapies. AREAS TIMELY FOR DEVELOPING RESEARCH: A multi-layer design and a zonal organization of the constructs may lead to achieve cartilage regeneration.

Growth factor sustained delivery from poly-lactic-co-glycolic acid microcarriers and its mass transfer modeling by finite element in a dynamic and static three-dimensional environment bioengineered with stem cells.

Poly-lactic-co-glycolic acid (PLGA) microcarriers (0.8 ± 0.2 µm) have been fabricated with a load of 20 µg/gPLGA by an emulsion-based-proprietary technology to sustained deliver human bone morphogenetic protein 2 (hBMP2), a growth factor largely used for osteogenic induction. hBMP2 release profile, measured in vitro, showed a moderate "burst" release of 20% of the load in first 3 days, followed by a sustained release of 3% of the load along the following 21 days. PLGA microbeads loaded with fluorescent marker (8 mg/gPLGA ) and hydroxyapatite (30 mg/gPLGA ) were also fabricated and successfully dispersed within three-dimensional (3D) alginate scaffold (Ca-alginate 2% wt/wt) in a range between 50 and 200 mg/cm3 ; the presence of microcarriers within the scaffold induced a variation of its stiffness between 0.03 and 0.06 MPa; whereas the scaffold surface area was monitored always in the range of 190-200 m2 /g. Uniform microcarriers dispersion was obtained up to 200 mg/cm3 ; higher loading values in the 3D scaffold produced large aggregates. The release data and the surface area were, then, used to simulate by finite element modeling the hBMP2 mass transfer within the 3D hydrogel bioengineered with stem cells, in dynamic and static cultivations. The simulation was developed with COMSOL Multiphysics® giving a good representation of hBMP2 mass balances along microbeads (bulk eroded) and on cell surface (cell binding). hBMP2 degradation rate was also taken into account in the simulations. hBMP2 concentration of 20 ng/cm3 was set as a target because it has been described as the minimum effective value for stem cells stimulation versus the osteogenic phenotype. The sensitivity analysis suggested the best microbeads/cells ratio in the 3D microenvironment, along 21 days of cultivations in both static and dynamic cultivation (perfusion) conditions. The simulated formulation was so assembled experimentally using human mesenchymal stem cells and an improved scaffold stiffness up to 0.09 MPa (n = 3; p ≤ 0.01) was monitored after 21 days of cultivation; moreover a uniform extracellular matrix deposition within the 3D system was detected by Von Kossa staining, especially in dynamic conditions. The results indicated that the described tool can be useful for the design of 3D bioengineered microarchitecture by quantitative understanding.

Biomimetic proteolipid vesicles for reverting GPI deficiency in paroxysmal nocturnal hemoglobinuria.

Nano-vesicular carriers are promising tissue-specific drug delivery platforms. Here, biomimetic proteolipid vesicles (BPLVs) were used for delivery of glycosylphosphatidylinositol (GPI)-anchored proteins to GPI deficient paroxysmal nocturnal hemoglobinuria (PNH) cells. BPLVs were assembled as single unilamellar monodispersed (polydispersity index, 0.1) negatively charged (ζ-potential, -28.6 ± 5.6 mV) system using microfluidic technique equipped with Y-shaped chip. GPI-anchored and not-GPI proteins on BPLV surface were detected by flow cytometry. Peripheral blood mononuclear cells (PBMCs) from healthy and PNH subjects were treated with BPLVs (final concentration, 0.5 mg/mL), and cells displayed an excellent protein uptake, documented by flow cytometry immunophenotyping and confocal microscopy. BPLV-treated cells stressed with complement components showed an increased resistance to complement-mediated lysis, both healthy and PNH PBMCs. In conclusion, BPLVs could be effective nanocarriers for protein transfer to targeted cells to revert protein deficiency, like in PNH disease. However, further in vivo studies are required to validate our preclinical in vitro results.

Ligand-Free Silver Nanoparticles: An Innovative Strategy against Viruses and Bacteria.

The spread of antibiotic-resistant bacteria and the rise of emerging and re-emerging viruses in recent years constitute significant public health problems. Therefore, it is necessary to develop new antimicrobial strategies to overcome these challenges. Herein, we describe an innovative method to synthesize ligand-free silver nanoparticles by Pulsed Laser Ablation in Liquid (PLAL-AgNPs). Thus produced, nanoparticles were characterized by total X-ray fluorescence, zeta potential analysis, transmission electron microscopy (TEM), and nanoparticle tracking analysis (NTA). A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was performed to evaluate the nanoparticles' cytotoxicity. Their potential was evaluated against the enveloped herpes simplex virus type 1 (HSV-1) and the naked poliovirus type 1 (PV-1) by plaque reduction assays and confirmed by real-time PCR and fluorescence microscopy, showing that nanoparticles interfered with the early stage of infection. Their action was also examined against different bacteria. We observed that the PLAL-AgNPs exerted a strong effect against both methicillin-resistant Staphylococcus aureus (S. aureus MRSA) and Escherichia coli (E. coli) producing extended-spectrum ß-lactamase (ESBL). In detail, the PLAL-AgNPs exhibited a bacteriostatic action against S. aureus and a bactericidal activity against E. coli. Finally, we proved that the PLAL-AgNPs were able to inhibit/degrade the biofilm of S. aureus and E. coli.

Tendon tissue engineering: An overview of biologics to promote tendon healing and repair.

Tendons are dense connective tissues with a hierarchical polarized structure that respond to and adapt to the transmission of muscle contraction forces to the skeleton, enabling motion and maintaining posture. Tendon injuries, also known as tendinopathies, are becoming more common as populations age and participation in sports/leisure activities increases. The tendon has a poor ability to self-heal and regenerate given its intrinsic, constrained vascular supply and exposure to frequent, severe loading. There is a lack of understanding of the underlying pathophysiology, and it is not surprising that disorder-targeted medicines have only been partially effective at best. Recent tissue engineering approaches have emerged as a potential tool to drive tendon regeneration and healing. In this review, we investigated the physiochemical factors involved in tendon ontogeny and discussed their potential application in vitro to reproduce functional and self-renewing tendon tissue. We sought to understand whether stem cells are capable of forming tendons, how they can be directed towards the tenogenic lineage, and how their growth is regulated and monitored during the entire differentiation path. Finally, we showed recent developments in tendon tissue engineering, specifically the use of mesenchymal stem cells (MSCs), which can differentiate into tendon cells, as well as the potential role of extracellular vesicles (EVs) in tendon regeneration and their potential for use in accelerating the healing response after injury.

Contribution of peripheral blood mononuclear cells isolated by advanced filtration system to myogenesis of human bone marrow mesenchymal stem cells co-cultured with myoblasts.

Background: Contribution of peripheral blood mononuclear cells (PBMCs) in myogenesis is still under debate, even though blood filtration systems are commonly used in clinical practice for successfully management of critic limb ischemia. Objectives: A commercial blood filter used for autologous human PBMC transplantation procedures is characterized and used to collect PBMCs, that are then added to well-established 2D in vitro myogenic models assembled with a co-culture of human bone marrow-derived mesenchymal stem cells (hBM-MSCs) and skeletal myoblasts (hSkMs) whit the aim of investigating their potential contribution to stem cell myogenic commitment. Methods: A commercial blood filter was physically and chemically studied to understand its morphological characteristics and composition. PBMCs were concentrated using this system, further isolated by Ficoll-Paque density gradient centrifugation, and then added in an upper transwell chamber to a 2D co-culture of hBM-MSCs and hSkMs. Myogenic commitment was investigated by RT-PCR, immunofluorescence, and flow cytometry immunophenotyping. Cytokine levels were monitored by ELISA assay in culture media. Results: The blood filtration system was disassembled and appeared to be formed by twelve membranes of poly-butylene terephthalate fibers (diameters, 0.9-4.0 µm) with pore size distribution of 1-20 µm. Filter functional characterization was achieved by characterizing collected cells by flow cytometry. Subsequently, collected PBMCs fraction was added to an in-vitro model of hBM-MSC myogenic commitment. In the presence of PBMCs, stem cells significantly upregulated myogenic genes, such as Desmin and MYH2, as confirmed by qRT-PCR and expressed related proteins by immunofluorescence (IF) assay, while downregulated pro-inflammatory cytokines (IL12A at day 14) along the 21 days of culture. Novelty: Our work highlights chemical-physical properties of commercial blood filter and suggests that blood filtrated fraction of PBMC might modulate cytokine expression in response to muscle injury and promote myogenic events, supporting their clinical use in autologous transplantation.

The Other Side of Plastics: Bioplastic-Based Nanoparticles for Drug Delivery Systems in the Brain.

Plastics have changed human lives, finding a broad range of applications from packaging to medical devices. However, plastics can degrade into microscopic forms known as micro- and nanoplastics, which have raised concerns about their accumulation in the environment but mainly about the potential risk to human health. Recently, biodegradable plastic materials have been introduced on the market. These polymers are biodegradable but also bioresorbable and, indeed, are fundamental tools for drug formulations, thanks to their transient ability to pass through biological barriers and concentrate in specific tissues. However, this "other side" of bioplastics raises concerns about their toxic potential, in the form of micro- and nanoparticles, due to easier and faster tissue accumulation, with unknown long-term biological effects. This review aims to provide an update on bioplastic-based particles by analyzing the advantages and drawbacks of their potential use as components of innovative formulations for brain diseases. However, a critical analysis of the literature indicates the need for further studies to assess the safety of bioplastic micro- and nanoparticles despite they appear as promising tools for several nanomedicine applications.

Editorial: Special Issue Development of Micro and Nano Systems for the Drug Delivery.

In this Issue, I have collected ten research papers and four review articles trying to describe the technologies that have evolved in the past ten years for the development of micro and nano systems for drug carry, targeting and delivery [...].

Synthesis and Characterization of a Novel Composite Scaffold Based on Hyaluronic Acid and Equine Type I Collagen.

Herein, the synthesis and characterization of a novel composite biopolymer scaffold-based on equine type I collagen and hyaluronic acid-were described by using a reaction in heterogeneous phase. The resulting biomimetic structure was characterized in terms of chemical, physical, and cytotoxicity properties using human-derived lymphocytes and chondrocytes. Firstly, FT-IR data proved a successful reticulation of hyaluronic acid within collagen structure with the appearance of a new peak at a wavenumber of 1735 cm-1 associated with ester carbonyl stretch. TGA and DSC characterizations confirmed different thermal stability of cross-linked scaffolds while morphological analysis by scanning electron microscopy (SEM) suggested the presence of a highly porous structure with open and interconnected void areas suitable for hosting cells. The enzymatic degradation profile confirmed scaffold higher endurance with collagenase as compared with collagen alone. However, it was particularly interesting that the mechanical behavior of the composite scaffold showed an excellent shape memory, especially when it was hydrated, with an improved Young's modulus of 9.96 ± 0.53 kPa (p ≤ 0.001) as well as a maximum load at 97.36 ± 3.58 kPa compared to the simple collagen scaffold that had a modulus of 1.57 ± 0.08 kPa and a maximum load of 36.91 ± 0.24 kPa. Finally, in vitro cytotoxicity confirmed good product safety with human lymphocytes (viability of 81.92 ± 1.9 and 76.37 ± 1.2 after 24 and 48 h, respectively), whereas excellent gene expression profiles of chondrocytes with a significant upregulation of SOX9 and ACAN after 10 days of culture indicated our scaffold's ability of preserving chondrogenic phenotype. The described material could be considered a potential tool to be implanted in patients with cartilage defects.