Cells encapsulated in alginate: a potential system for delivery of recombinant proteins to malignant brain tumours
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Updated: Jul 29, 2026
Generation of Alginate Microspheres for Biomedical Applications
Published on: August 12, 2012
T A Read1, V Stensvaag, H Vindenes
1Department of Anatomy and Cell Biology, University of Bergen, Norway. t-a.read@pki.uib.no
Abstract:
Growth and progression of malignant brain tumours occurs in a micromilieu consisting of both tumour and normal cells. Several proteins have been identified with the potential of interfering directly with tumour cells or with the neovascularisation process, thereby inhibiting tumour growth. A continuous delivery of such inhibitory proteins to the tumour microenvironment by genetically engineered cells could theoretically be of considerable therapeutic importance. In this study we have investigated the growth characteristics of cells encapsulated in alginate, which represents a potential delivery system for recombinant proteins that may have antitumour effects. Three different cell lines, NHI 3T3, 293 and BT4C were encapsulated in alginate, which is an immuno-isolating substance extracted from brown seaweed. The encapsulated cells were observed at specific intervals during a 4-month period after in vitro propagation and as transplants into the cortex of BD-IX rats. Morphological studies showed that encapsulated cells proliferated and formed spheroids within the alginate in the in vitro cultures and after implantation into the brain. Even after 4 months in vivo a substantial amount of living cells were observed within the alginate beads. A vigorous infiltration of mononuclear cells was observed in the brain bordering the alginate beads, one week after implantation. However, there was a gradual decrease of mononuclear cells at the border zone beyond the first week of implantation. The majority of inflammatory cells were reactive microglia and invading monocytes, as verified by immunohistochemistry. The data further shows that alginate encapsulated cells can be frozen in liquid N2 and will retain their viability and proliferative capacity.
Insights
Alginate encapsulation supports cell survival and proliferation for potential brain tumor therapies. Encapsulated cells can be cryopreserved, maintaining their therapeutic potential for sustained delivery.
Area of Science:
- Biomedical Engineering
- Neuro-oncology
- Drug Delivery Systems
Background:
- Malignant brain tumors grow within a complex microenvironment involving tumor and normal cells.
- Proteins that inhibit tumor growth or neovascularization offer therapeutic potential.
- Genetically engineered cells could provide continuous delivery of therapeutic proteins to the tumor microenvironment.
Purpose of the Study:
- To investigate the growth characteristics of cells encapsulated in alginate as a potential delivery system for anti-tumor proteins.
- To assess the viability and proliferation of encapsulated cells in vitro and in vivo.
- To evaluate the host response to alginate-encapsulated cell implants in a rat brain model.
Main Methods:
- Encapsulation of three cell lines (NIH 3T3, 293, BT4C) in alginate.
- In vitro culture and in vivo transplantation into the cortex of BD-IX rats.
- Morphological studies, viability assessment, and immunohistochemistry over a 4-month period.
- Cryopreservation of encapsulated cells in liquid nitrogen.
Main Results:
- Encapsulated cells proliferated and formed spheroids in vitro and in vivo.
- A substantial number of living encapsulated cells were observed up to 4 months post-implantation.
- Host inflammatory response (mononuclear cells, microglia, monocytes) was observed around the implants but decreased over time.
- Alginate-encapsulated cells retained viability and proliferative capacity after cryopreservation.
Conclusions:
- Alginate encapsulation is a viable method for supporting cell survival and proliferation for potential therapeutic protein delivery in the brain.
- Encapsulated cells demonstrate long-term viability in vivo and can be cryopreserved, offering a stable platform for sustained therapeutic agent release.
- The immuno-isolating nature of alginate may mitigate host rejection, facilitating the use of encapsulated cells for brain tumor treatment.
