Bone marrow mesenchymal stem cells (BM-MSCs) and cartilage fragments were evaluated for their ability to enhance cartilage formation in an ex-vivo osteochondral defect model. BM-MSCs alone, cartilage fragments alone, or a combination of BM-MSCs and cartilage fragments were seeded into osteochondral defects. The combination of BM-MSCs and cartilage fragments showed improved cartilage formation and defect filling compared to BM-MSCs or cartilage fragments alone, as seen on histological and biochemical analysis. The results suggest that a combination of BM-MSCs and cartilage fragments may provide a more effective approach for cartilage repair.

1. Bone marrow mesenchymal stem cells and cartilage fragments enhance chondrogenesis
Gari M1,2,3, Alsehli H 1,2, Abbas M2 , Alkaff M2, Kafienah W2,4, Chaudhary AG1,3, Abuzenadah A1,3, Al Qahtani M1,3, Gauthaman K1,2.
1Stem Cell Unit, Centre of Excellence in Genomic Medicine Research, King Abdulaziz University, Kingdom of Saudi Arabia
2Department of Orthopaedic Surgery, Faculty of Medicine, King Abdulaziz University, and Sheikh Salem Bin Mahfouz Scientific Chair for Treatment of Osteoarthritis by Stem Cells,
Kingdom of Saudi Arabia
3Department of Medical Laboratory Technology, Faculty of Applied Medical Sciences, King Abdulaziz University, Kingdom of Saudi Arabia
4School of Cellular and Molecular Medicine, University of Bristol, United Kingdom
Introduction
Cartilage-subchondral bone interphase and the prevailing cellular
and molecular microenvironment play a significant role in
osteoarthritis (OA). To understand whether cellular/local
microenvironmental cues contribute to better cartilage repair, in
the present ex-vivo study, we evaluated the chondrogenic
differentiation and repair of critical size defect in an explant
osteochondral model using bone marrow derived mesenchymal
stem cells (BM-MSCs) and homogenised cartilage.
Informed patient consent was obtained for collecting BM-MSCs,
osteochondral bone, and cartilage from undamaged areas from
patients undergoing total knee arthroplasty. Bone pieces were
trimmed to 1cm (w) x 1cm (b) x 1cm (h) and a central drill defect
(~1mm) was made. Chondrogenic repair was evaluated by
seeding the osteochondral bone defect (OBD) with either BM-
MSCs (1x106cells) pellet (Group II), homogenized cartilage pellet
(Group III) or a combination of both BM-MSCs (0.5x106cells)
and homogenized cartilage as pellet (Group IV). OBD with no
added cells or tissue served as control. Similar sized tissue pellets
were used for all experimental arms. Samples from all four
groups were maintained in standard BM-MSC chondrogenic
medium up to 28 days. The tissue repair was analyzed by
histology, phase contrast imaging and biochemical analysis.
Materials and Methods
References
1. Chen CC, Liao CH, Wang YH et al. 2011. Cartilage Fragments from Osteoarthritic Knee Promote
Chondrogenesis of Mesenchymal Stem Cells without Exogenous Growth Factor Induction. Journal
of Orthopaedic Research, 30(3):393-400.
2. Leyh M, Seitz A, Durselen et al 2014. Subchondral bone influences chondrogenic differentiation and
collagen production of human bone marrow-derived mesenchymal stem cells and articular
chondrocytes. Arthritis Res Ther. 16(5):453.
Figure 1: A) Explant culture images (Upper Panel) showing the osetochondral bone
with central drill defect (circular dotted lines) with or without cells as mentioned;
B) their respective phase contrast images (Middle Panel) taken at the bone defect area
on day 14 Central drill defect is represented within the dotted lines. In the control
group the defect area is seen empty, whereas the other groups shows the defect area
being filled with the respective cell types; C) H&E images (Lower Panel) of the same
at low magnification.
Figure 2: H&E staining of demineralized tissue sections of the paraffin embedded
bone tissue following 28 days of ex-vivo culture showed neochondrocyte formations
(indicated by arrows) that were less in the MSCs group (Group II) and more in the
MSCs + cartilage group (Group IV).
Figure 3: a) Toluidine blue staining of demineralized tissue sections of the paraffin
embedded bone tissue following 28 days of ex-vivo culture showed positive staining
indicative of collagen content; b) Sircol assay showing the secreted collagen levels at
days 7, 14 and 21. The amount of secreted collagen is more in Group II (BM-MSCs) and
Group IV (BM-MSCs + Cartilage) compared to rest of the groups. The values are shown
as mean ± SEM from three independent samples.
a
We would like to acknowledge the financial support provided by the “Sheikh
Salem Bin Mahfouz Scientific Chair for Treatment of Osteoarthritis by Stem
Cells”; the Stem Cell Lab at CEGMR and the Orthopedics Stem Cell
Research Lab at King Abdulaziz University Hospital for supporting this study.
Acknowledgment
MSCs and cartilage fragments together provided better cartilage
formation and defect filling in a human ex-vivo osteochondral
model. Further analysis of sub-fragments could help design more
effective methods for the delivery of therapeutic chondrogenic
MSCs.
Discussion and Conclusion
Results
May 8th – 11th, 2015