October 21, 2020 by admin 0 Comments

Design and manufacturing of bioprinted gellan gum-based constructs representative of the articular cartilage

Authors
Gianluca Ciardelli, Piergiorgio Gentile, Chiara Tonda Turo
Abstract
Articular cartilage (AC) is a highly specialized tissue which exhibit topographical heterogeneity in terms of matrix composition and mechanical properties. Due to its avascular nature AC shows limited regenerative ability, therefore representing an excellent subject for tissue engineering (TE). Particularly, bioprinting is an emerging additive manufacturing technology that has already demonstrated its potential use in regenerative medicine and cartilage TE. It allows to recapitulate the tissues microstructure by a controlled deposition of “bioinks”, suspensions of cells alone or encapsulated in biomaterials. As cells source, mesenchymal stem cells and chondrocytes, both naturally found in AC, are mainly selected. Hydrogels are largely used as biomaterials for their ability to resemble soft tissues extracellular matrix (ECM), providing an ideal micro-environment for the embedded cells survival, proliferation and differentiation. Hydrogels are produced from synthetic and natural polymers, including gellan gum (GG), a biocompatible polysaccharide that has gained interest in cartilage TE because of its structural similarity to cartilage glycosaminoglycans (GAGs) and chondrogenic potential. The aim of this work was the design and manufacturing of 3D constructs mimicking AC by extrusion bioprinting. Particularly, this thesis objectives (OBJ) were: the synthesis and characterization (physico-chemical, morphological, mechanical) of methacrylated GG-based hydrogels subjected to a dual physical and photo-chemical crosslinking (OBJ1); the subsequent biofabrication via Rokit INVIVO bioprinter of in vitro constructs (OBJ2) and biological characterization of cell-laden constructs in terms of cells viability and AC tissue formation (OBJ3). The final stage of this work dealt with the manufacturing of osteoarthritis (OA) in vitro models, via culturing healthy models in cytokine-enriched culture medium, for future analysis on novel OA therapeutic treatments. Firstly, the success of GG methacrylate (GGMA) synthesis was demonstrated through FTIR and XPS analysis. Then, 4 photo-curable hydrogels were prepared: pure GGMA 2% w/v (GG2) and 3% w/v (GG3), and GGMA (respectively 2% w/v and 0.75% w/v) combined with 5% w/v manuka honey (GG/MH) and 10% w/v gelatin (GG/GEL). Gelation analysis at room temperature showed that GG3 and GG/GEL underwent sol-gel transition in ~1 minute, while GG2 and GG/MH in ~3 minute. Water uptake (WU) analysis demonstrated the strong hydrophilic nature of these hydrogels, reaching WU values up to ~1700%. Morphological analysis evidenced that they had an interconnected porous morphology with a mean pore diameter in the range 100-200 μm, suitable for AC applications. Similarly, mechanical analysis showed that hydrogels had a compressive Young’s modulus between ~25 and ~16 kPa, comparable to other natural hydrogels found in literature. GG2 and GG/MH hydrogels were selected as bioinks encapsulating human TERT immortalised stem cells differentiated into chondrocytes (Y201-C; 7x106 cells/ml). The double-crosslinked bioinks were successfully printed into stable constructs. Live/Dead assay demonstrated high cell viability for both bioprinted constructs. The GAGs quantification assay showed that Y201-C GAGs production increased over time in both hydrogels. Finally, scanning electron microscopy analysis showed that cells exhibited a typical chondrocytes rounded-shaped morphology and tended to aggregate in both healthy and OA GG2 constructs .

October 1, 2020 by admin 0 Comments

3D printing of self-healing ferrogel prepared from glycol chitosan, oxidized hyaluronate, and iron oxide nanoparticles

Authors
Eun Seok Ko a,1, Choonggu Kim a,1, Youngtae Choi a, Kuen Yong Lee a,b
Abstract
Hydrogel systems that show self-healing ability after mechanical damage are receiving increasing attention. However, self-healing hydrogels suitable for biomedical applications are limited owing to complex preparation methods. Furthermore, few studies have demonstrated the self-healing property of ferrogels. In this study, we demonstrated that glycol chitosan (GC) and oxidized hyaluronate (OHA) can be used to form a self-healing ferrogel in the presence of superparamagnetic iron oxide nanoparticles (SPIONs) without additional chemical cross-linkers. The overall characteristics of GC/OHA/SPION ferrogel varied based on the GC/OHA ratio, SPION content, and total polymer concentration. Interestingly, GC/OHA/SPION ferrogel was used to fabricate 3D-printed constructs of various shapes via an extrusion printing method. These constructs were responsive to the magnetic field, suggesting their potential application in 4D printing. This approach to developing self-healing ferrogels with biocompatible polysaccharides may prove useful in designing and fabricating drug delivery systems and tissue engineering scaffolds, via 3D printing.

June 15, 2020 by admin 0 Comments

Dual-crosslinked methylcellulose hydrogels for 3D bioprinting applications

Authors
Ji Youn Shin (a), Yong Ho Yeo (a), Jae Eun Jeong (b), Su A. Park (b), Won Ho Park (a)
Abstract
Thermo-sensitive methylcellulose (MC) hydrogel has been widely used as a scaffold material for biomedical applications. However, due to its poor mechanical properties, the MC-based hydrogel has rarely been employed in 3D bioprinting for tissue engineering scaffolds. In this study, the dual crosslinkable tyramine-modified MC (MC-Tyr) conjugate was prepared via a two-step synthesis, and its hydrogel showed excellent mechanical properties and printability for 3D bioprinting applications. The MC-Tyr conjugate formed a dual-crosslinked hydrogel by modulating the temperature and/or visible light. A combination of reversible physical crosslinking (thermal crosslinking) and irreversible chemical crosslinking (photocrosslinking) was used in this dual crosslinked hydrogel. Also, the photocrosslinking of MC-Tyr solution was facilitated by visible light exposure in the presence of biocompatible photoinitiators (riboflavin, RF and riboflavin 5’-monophophate, RFp). The RF and RFp were used to compare the cytotoxicity and salting-out effect of MC-Tyr hydrogel, as well as the initiation ability, based on the difference in chemical structure. Also, the influence of the printing parameters on the printed MC hydrogel was investigated. Finally, the cell-laden MC-Tyr bioink was successfully extruded into stable 3D hydrogel constructs with high resolution via a dual crosslinking strategy. Furthermore, the MC-Tyr scaffolds showed excellent cell viability and proliferation.

June 1, 2020 by admin 0 Comments

All About Extracellular Marix, And its application

ROKIT Open Innovation
All About Extracellular Marix, And its application
- 2020. 06. 12. FRI. 11:00 AM -
OVERVIEW

"Welcome to ROKIT & Calia Webinar"

This webinar will explain what is Extracellular Matrix,
what are the research areas ECM is applied,
and what are the limitations of current ECM products and the solution to it.

* This webinar is hosted by ROKIT Healthcare INC and CALIA

Check out the webinars for more details.
SPEAKER

Joshua Jaeyun Kim, PhD

  • HumaTein/Bioink SBU President

Career Highlight

  • Ph.D., Dept of Biomedical Engineering, Boston University
  • Postdoctoral Research Associate, Boston University
INFORMATION
Subject
Date
Live Platform
All About Extracellular Marix, And its application
2020.06.12. FRI 11:00 AM
ZOOM
INVITATION
Please RSVP today, we will send you ZOOM link soon!

Privacy Policy

Collection of Information : Name, Email, Institution, Dept Name Purpose of Collection : Contact Period of Use : In principle, after the purpose of collecting and using personal information is achieved, such information shall be destroyed without delay. However, personal information may be kept for a certain period as specified in the relevant statutes, if it is necessary to preserve it according to the provisions of the relevant statutes, as follows. - Records on consumer complaints or dispute handling : 3 years (Law on Consumer Protection in Electronic Commerce, etc.) - Agree to collect and use of personal information above. (you can inquire after consent)

ROKIT HEALTHCARE is a 4D Bioprinting and Biotechnology company based in South Korea and is committed to bettering humanity through our contributions to the field of regenerative medicine.
Question
ROKIT Healthcare INC. HYEJOO SON

May 29, 2020 by admin 0 Comments

3D-Bioprinted Aptamer-Functionalized Bio-inks for Spatiotemporally Controlled Growth Factor Delivery

Authors
Deepti Rana, Vasileios D. Trikalitis (Contributor), Vincent R. Rangel (Contributor), Ajoy Kumar Kandar (Contributor), Nasim Salehi Nik (Contributor), Jeroen Rouwkema* (Contributor)
Abstract
Introduction Spatiotemporally controlled growth factors delivering systems are crucial for tissue engineering. However, most of the current strategies for growth factors delivery often focuses on the immobilization or coupling of growth factors within the engineered matrices (hydrogel) via various linker proteins or peptides. These systems provide passive release rates and growth factor delivery on demand, but fail to adapt their release rates in accordance with the tissue development. To overcome this limitation, the present study employed nucleic acid based aptamers for achieving spatiotemporally controlled growth factor delivery. Aptamers are affinity ligands selected from DNA/RNA libraries to recognize proteins with high affinity and specificity.1 Aptamer based growth factor delivery systems are able to load/release multiple growth factors on demand with high specificity. In the present study, the authors have 3D-bioprinted aptamer-functionalized bio-inks to evaluate their potential for growth factor sequestering, programmable release and for studying their effect on vascular network formation. Methods The aptamer-functionalized hydrogels were prepared via photo-polymerization of gelatin methacryloyl (GelMA) and acrydite functionalized aptamers having sequence specific for binding to vascular endothelial growth factor (VEGF165). Visible light photoinitiator, tris(2,2′-bipyridyl)dichloro-ruthenium(II) hexahydrate with sodium persulfate was used. The 3D-bioprinting experiments were carried out using Rokit Invivo 3D printer. The viscoelastic properties of the bio-inks were evaluated and compared with control GelMA bio-ink. To study the programmable growth factor release efficiency, VEGF antibody immunostaining was used. For studying the effect of triggered growth factor release on vascular network formation, human umbilical vein endothelial cells (HUVECs) and mesenchymal stem cells (MSCs) were encapsulated within the bio-inks. Results & Discussion The results obtained from VEGF antibody immunostainings confirmed the sequestration and triggered release of VEGF in response to complementary sequence addition from the 3D bioprinted construct after 5 days of culture. The bioprinted construct showed high cellular viability. The F-Actin/DAPI staining showed cellular sprouting and vascular network formation within the 3D printing aptamer functionalized bio-ink regions. In addition, the endothelial cells showed variations in cellular organization based on the VEGF bound aptamer availability within the bioprinted construct. These observations altogether confirms the bioactivity of VEGF bound aptamers within the printed constructs. Conclusions The present study shows the vasculogenic potential of 3D bioprinted aptamer-functionalized bio-inks via spatiotemporally controlling VEGF availability within the hydrogel system. Acknowledgements: This work is supported by an ERC Consolidator Grant under grant agreement no 724469. References 1. M.R. Battig, et. al., J. Am. Chem. Soc. 134 (2012) 12410-12413.

January 1, 2019 by admin 0 Comments

3D Bioprinting of human adipose stem cells (hADSCs) encapsulated hyaluronic acid (HA) based biomimetic double crosslinked hydrogel bioink for cartilage tissue engineering (CTE)

Authors
Parikshit Banerjee
Abstract
Articular cartilage covers the edges of the bones and provides wear resistant load bearing capacity which ultimately supports the flexible joint movement. Therefore, once these articular cartilages get damaged, they limit the free joint movements in patients and cause severe complication. Also, articular cartilage is avascular in nature, which also restricts its ability to repair itself after any damage. To address these issues associated with articular cartilage damage, cartilage tissue engineering (CTE) has been introduced. CTE helps in repairing or regenerating damaged cartilages by using a combined strategy which involves cell, growth factors, and biomaterial scaffolds. Hydrogel with the ability to absorb a large amount of water viewed as an ideal material for cartilage mimetic scaffold owing to the similarity between the hydrogel and native cartilage. Combining stem cell or chondrocytes with hydrogel scaffold is regarded as a promising approach for CTE. This strategy is capable of supporting highly dense cell population, cell attachment, homogeneous cell distribution, and also offer an ideal microenvironment for cell growth and differentiation. Unfortunately, developing hydrogel scaffold with required structural integrity is a major issue that limits the application of hydrogel in CTE. Therefore, to address the problems associated with existing CTE, this thesis aimed to utilize 3D bioprinting to print cartilage constructs by combining adipose-derived stem cells (ADSCs) and hyaluronic acid (HA) based hydrogels. First, to develop a new cartilage extracellular matrix (ECM) mimetic hydrogel system, we synthesized biotinylated-hyaluronic acid (HA-Biotin) and confirmed the successful grafting of biotin with HA trough Fourier Transform Infrared Spectroscopy (FTIR) analysis. Next, HA-Bio hydrogel was prepared and Streptavidin was mixed with this hydrogel to form partially crosslinked HA-based hydrogel through non-covalent bonding between biotin and streptavidin. Addition of streptavidin also supports higher cell attachment due to the presence of cell adhesion sites in streptavidin. After that, partially crosslinked HA-Bio-Streptavidin (HBS) hydrogel was mixed with sodium alginate and subsequently printed using Rokit INVIVO bioprinter. After printing, 3D scaffolds were submerged into CaCl2 solution achieve ionic crosslinking through ion transfer between sodium alginate and CaCl2. Different parameters such as fiber formation, self-supporting ability, printing resolution, and crosslinker concentration were optimized to get desired 3D printed constructs. In vitro cell proliferation and live/dead staining assay were also performed on 3D cell-laden scaffolds. The result showed that partially crosslinking the biotinylated-HA based hydrogel with streptavidin has a significant effect on printability. Morphological analysis of optimal 3D printed scaffold showed clearly visible pores with desired shape and geometry. Favorable cell proliferation and growth was also observed in 3D HBSA based hydrogel scaffolds. These result further confirmed that double crosslinking HA-based hydrogel could be a good choice for 3D bioprinting based tissue engineering.