1. In Vitro Evaluation of a Rapidly In situ Forming Hyaluronic acid Hydrogel as a Carrier for Mesenchymal Stem Cell Delivery
Elaheh Jooybar1*, Mohammad J. Abdekhodaie1, Mansour Alvi2, Marcel Karperien3, Pieter J. Dijkstra3
Chemical Engineering, Sharif University of Technology , Tehran, Iran
Canadian Center for Regenerative Therapy, Toronto, ON, Canada
Department of Developmenta Bioengineering, University of Twente, Enschede, The Netherlands
Objectives
Results
Methods
In situ delivery of cells is expected to enhance tissue regeneration, especially delivery of mesenchymal stem cells (MSC), as they can differentiate to many cell types [1]. To have a proper therapeutic effects, cells should remain alive and metabolically active in the defect site, thus having a good carrier for cell delivery is crucial. In this study, an injectable hyaluronic acid hydrogel was developed for delivery of human MSCs, which can be applied in a target area with a one-step minimal invasive method.
The mild gelation condition of HA hydrogel helps the encapsulated cells to remain alive during crosslinking procedure. The cells in both HA and HA-PL hydrogels remain viable for at least one month. In HA hydrogel the cells do not attach and retain a round morphology, while in HA-PL construct the cells attach and spread (Fig. 5). The encapsulated cells can proliferate in PL loaded hydrogel while the DNA amount decreases during time in HA construct showing the cells do not proliferate (Fig. 6)
Hyaluronic acid-tyramine (HA-TA) conjugate was synthesized, and enzymatically crosslinked by addition of Horseradish peroxidase (HRP) and hydrogen peroxide (H2O2) (Fig. 1). The hydrogel can be injected into the defect site with a double syringe (Fig. 2). To enhance the bioactivity of the hydrogel, platelet lysate (PL) was incorporated into the constructs. Platelet lysate is an autologous and inexpensive source of abundant growth factors and cytokines which is obtained by lysing the platelets (Fig. 3). Also, PL contains a lot of proteins that is suitable for cell adhesion. The hMSCs and PL were incorporated in the hydrogel during the gelation procedure (Fig. 4). The developed hydrogel has the three main components of tissue engineering, which are scaffold, cells and growth factors. . HA
HRP enzyme
HA-TA
Hydrogel
H2O2 +
HA hydrogel
200 μm
Fig. 1 HA-TA crosslinking by addition of HRP and H2O2
Platelet lysate
Stem cell
HA-PL
HA+H2O2
HA+HRP
200 μm
Fig. 5 F-Actin and DAPI staining of the encapsulated cells after 3 days
Defect
Fig. 4 HA hydrogel incorporated with hMSCs and platelet lysate
Conclusions
An injectable hyaluronic acid hydrogel was developed and incorporated with platelet lysate. The presence of PL in the hydrogel structure has a great impact on the cell attachment and proliferation. The proposed injectable hydrogel is an easy-to-apply approach and can be used for cell delivery purposes in tissue regeneration.
Fig. 2 Injectable hydrogel to fill the defect that is injected by a double syringe
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References
Fig. 6 DNA content in HA and HA-PL hydrogels. *** p-value <0.001.
1. Jin, R., et al. (2010). Enzymatically crosslinked dextran-tyramine hydrogels as injectable scaffolds for cartilage tissue engineering. Tissue Engineering Part A, 16(8),
Fig. 3 Platelet lysate as an autologous source of growth factors obtained by platelet lysis