Biobased extracts comprise various bioactive components and they are widely used in tissue engineering applications to increase bioactivity as well as physical characteristics of biomaterials. Among animal sources, garden snail Helix aspersa has come into prominence with its antibacterial and regenerative extracts and show potential in tissue regeneration. Thus, in this study, bioactive H. aspersa extracts (slime, mucus) were loaded in chitosan (CHI) matrix to fabricate porous scaffolds for hard tissue regeneration. Physical, chemical properties, antimicrobial activity was determined as well as in vitro bioactivity for bone and cartilage regeneration. Mucus and slime incorporation enhanced mechanical properties and biodegradation rate of CHI matrix. Scanning electron microscopy images showed that the average pore size of the scaffolds decreased with higher extract content. Mucus and slime extracts showed antimicrobial effect on two bacterial strains. In vitro cytotoxicity, osteogenic and chondrogenic activity of the scaffolds were evaluated with Saos-2 and SW1353 cell lines in terms of Alkaline phosphatase activity, biomineralization, GAG, COMP and hydroxyproline content. Cell viability results showed that extracts had a proliferative effect on Saos-2 and SW1353 cells when compared to the control group. Mucus and slime extract loading increased osteogenic and chondrogenic activity. Thus, the bioactive extract loaded CHI scaffolds showed potential for bone and cartilage regeneration with enhanced physical properties and in vitro bioactivity.

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Regenerative medicine is a scientific field that improves and repairs diseased and injured tissues. Three-dimensional (3D) printing is an innovative technology that provides a new application field for regenerative medicine. 3D printed scaffolds by programming pore sizes and shapes serve as a temporary basis for cells until the natural extracellular matrix (ECM) is reconstructed. Dermal fibroblasts are mesenchymal cells located in the dermal skin layer that produce and organize ECM components. They play an essential role in skin wound healing and fibrosis. The aim of this study is to analyze the viability, adhesion, distribution, and collagen IV expression of human dermal fibroblasts (HDFs) seeded on 3D printed polylactic acid (PLA), polyethylene terephthalate (PET), and poly-ε-caprolactone (PCL) scaffolds in vitro. HDFs were seeded on scaffolds or tissue culture plastic plates as control and were cultured for 1 and 3 days. 3D PLA, PCL, and PET scaffolds were prepared using a custom made fused deposition modeling printer. The cell viability was measured by WST-1 assay on days 1 and 3. The cell adhesion was evaluated by scanning electron microscopy (SEM).The distribution was analyzed by hematoxylin and eosin (H&E) staining. Collagen IV expression was analyzed by immunohistochemical (IHC) staining.On day 1, the viability of HDFs on the 3D PLA scaffolds was significantly higher than PCL scaffolds. On day 3, the viability of HDFs on 3D PLA and PET scaffolds was significantly higher than PCL scaffolds. SEM images showed that HDFs on 3D PLA scaffolds attached the surfaces, filled the interfiber gaps and maintained their tissue specific morphology on day 3 compared to PCL and PET scaffolds. Histological images stained with H&E demonstrated that the distribution of HDFs on 3D PLA scaffolds was uniform on days 1 and 3. Collagen IV staining was more intense in HDFs on 3D PLA scaffolds on days 1 and 3. This study shows that 3D PLA scaffolds create a appropriate environment for cell viability, adhesion, distribution and may provide a high advantage in skin tissue regeneration.

Tissue engineering is an interdisciplinary field for the design of functional constructs that aid to repair damaged or diseased tissue. Threedimensional (3D) printing is a growing technology that offers new opportunities for tissue engineering. Thermoplastic polyurethane (TPU) is a member of the polyurethane class. TPUs are commonly used in medical applications with their biocompatible, superior mechanical properties and shape memory behavior. Macrophages are key regulators of tissue homeostasis, inflammation, and regeneration. They play crucial roles in initial immune response to implants. In this study, we aimed to investigate the viability, adhesion, and distribution properties of human THP-1 macrophages seeded on 3D printed TPU scaffolds in vitro. The expression of CD68 and CD10 was also analyzed in human THP-1 macrophages on 3D TPU scaffolds. THP-1 macrophages treated with phorbol-12-myristate-13-acetate (PMA) were seeded on 3D TPU scaffolds or tissue culture plastic plates as control and cultured for 1, 3, 7, and 14 days. 3D TPU scaffolds were prepared using a custom made fused deposition modeling printer. The cell viability was measured by WST-1 assay on days 1 and 3. The cell adhesion was evaluated by scanning electron microscopy (SEM). The cell distribution was analyzed by hematoxylin and eosin (H&E) staining. Expression of CD10 and CD68 was analyzed by immunohistochemical (IHC) staining. The viability of THP-1 macrophages on 3D TPU scaffolds was lower than their control groups on days 1 and 3. SEM images showed THP-1 macrophage attachment on the 3D TPU scaffold surface with round and elongated morphologies. H&E staining demonstrated that THP-1 macrophages showed eosinophilic cytoplasm and large nuclei. CD68 staining was more intense in THP-1 macrophages on 3D TPU scaffolds on day 3 compared to days 1, 7 and 14. CD10 staining was more intense on day 1 compared to days 3, 7, and 14. Our results show that 3D TPU scaffolds are biocompatible with macrophages and might be a potential biomaterial for medical applications.

Regeneration of osteochondral tissue with its layered complex structure and limited self-repair capacity has come into prominence as an application area for biomaterial design. Thus, literature studies have aimed to design multilayered scaffolds using natural polymers to mimic its unique structure. In this study, fabricated scaffolds are composed of transition layers both chemically and morphologically to mimic the gradient structure of osteochondral tissue. The aim of this study is to produce gradient chitosan (CHI) scaffolds with bioactive snail (Helix aspersa) mucus (M) and slime (S) extract and investigate the structures regarding their physicochemical, mechanical, and morphological characteristics as well as in vitro cytocompatibility and bioactivity. Gradient scaffolds (CHI-M and CHI-S) were fabricated via a layer-by-layer freezing and lyophilization technique. Highly porous and continuous 3D structures were obtained and observed with SEM analysis. In addition, scaffolds were physically characterized with water uptake test, micro-CT, mechanical analysis (compression tests), and XRD analysis. In vitro bioactivity of scaffolds was investigated by co-culturing Saos-2 and SW1353 cells on each compartment of gradient scaffolds. Osteogenic activity of Saos-2 cells on extract loaded gradient scaffolds was investigated in terms of ALP secretion, osteocalcin (OC) production, and biomineralization. Chondrogenic bioactivity of SW1353 cells was investigated regarding COMP and GAG production and observed with Alcian Blue staining. Both mucus and slime incorporation in the chitosan matrix increased the osteogenic differentiation of Saos-2 and SW1353 cells in comparison to the pristine matrix. In addition, histological and immunohistological staining was performed to investigate ECM formation on gradient scaffolds. Both characterization and in vitro bioactivity results indicated that CHI-M and CHI-S scaffolds show potential for osteochondral tissue regeneration, mimicking the structure as well as enhancing physical characteristics and bioactivity.