Papain-induced in vitro disc degeneration model for the study of injectable nucleus pulposus therapy

Chan, Samantha C. W.; Bürki, Alexander; Bonel, Harald M.; Benneker, Lorin M.; Gantenbein-Ritter, Benjamin (2013). Papain-induced in vitro disc degeneration model for the study of injectable nucleus pulposus therapy. Spine Journal, 13(3), pp. 273-283. Elsevier 10.1016/j.spinee.2012.12.007

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BACKGROUND CONTEXT

Proteolytic enzyme digestion of the intervertebral disc (IVD) offers a method to simulate a condition of disc degeneration for the study of cell-scaffold constructs in the degenerated disc.

PURPOSE

To characterize an in vitro disc degeneration model (DDM) of different severities of glycosaminoglycans (GAG) and water loss by using papain, and to determine the initial response of the human mesenchymal stem cells (MSCs) introduced into this DDM.

STUDY DESIGN

Disc degeneration model of a bovine disc explant with an end plate was induced by the injection of papain at various concentrations. Labeled MSCs were later introduced in this model.

METHODS

Phosphate-buffered saline (PBS control) or papain in various concentrations (3, 15, 30, 60, and 150 U/mL) were injected into the bovine caudal IVD explants. Ten days after the injection, GAG content of the discs was evaluated by dimethylmethylene blue assay and cell viability was determined by live/dead staining together with confocal microscopy. Overall matrix composition was evaluated by histology, and water content was visualized by magnetic resonance imaging. Compressive and torsional stiffness of the DDM were also recorded. In the second part, MSCs were labeled with a fluorescence cell membrane tracker and injected into the nucleus of the DDM or a PBS control. Mesenchymal stem cell viability and distribution were evaluated by confocal microscopy.

RESULTS

A large drop of GAG and water content of the bovine disc were obtained by injecting >30 U/mL papain. Magnetic resonance imaging showed Grade II, III, and IV disc degeneration by injecting 30, 60, and 150 U/mL papain. A cavity in the center of the disc could facilitate later injection of the nucleus pulposus tissue engineering construct while retaining an intact annulus fibrosus. The remaining disc cell viability was not affected. Mesenchymal stem cells injected into the protease-treated DDM disc showed significantly higher cell viability than when injected into the PBS-injected control disc.

CONCLUSIONS

By varying the concentration of papain for injection, an increasing amount of GAG and water loss could be induced to simulate the different severities of disc degeneration. MSC suspension introduced into the disc has a very low short-term survival. However, it should be clear that this bovine IVD DDM does not reflect a clinical situation but offers exciting possibilities to test novel tissue engineering protocols.

Item Type:	Journal Article (Original Article)
Division/Institute:	04 Faculty of Medicine > Pre-clinic Human Medicine > Institute for Surgical Technology & Biomechanics ISTB [discontinued] 04 Faculty of Medicine > Department of Radiology, Neuroradiology and Nuclear Medicine (DRNN) > Institute of Diagnostic, Interventional and Paediatric Radiology 04 Faculty of Medicine > Department of Orthopaedic, Plastic and Hand Surgery (DOPH) > Clinic of Orthopaedic Surgery
UniBE Contributor:	Chan, Samantha (A), Bürki, Alexander, Bonel, Harald Marcel, Benneker, Lorin Michael, Gantenbein, Benjamin
Subjects:	500 Science > 570 Life sciences; biology 600 Technology > 610 Medicine & health
ISSN:	1529-9430, 1878-1632
Publisher:	Elsevier
Language:	English
Submitter:	Stephanie Schmutz
Date Deposited:	04 Apr 2014 11:44
Last Modified:	29 Mar 2023 23:33
Publisher DOI:	10.1016/j.spinee.2012.12.007
PubMed ID:	23353003
URI:	https://boris.unibe.ch/id/eprint/42740