About our lab
We are examining cell-cell and cell-matrix interactions and intercellular and intracellular signaling pathways that stem cells use during differentiation. These studies aim to increasing understanding of stem cell differentiation into chondrocytes. We are studying this process in vivo and with mesenchymal progenitor and stem cells of various sources in the in vitro chondrogenesis systems developed by our laboratory.
Mesenchymal stem cells (MSCs) remain poorly defined. We are characterizing these cells from patients, examining the relationships of age, pathology and other characteristics to the proliferation and skeletal tissue differentiation capabilities of MSCs in a large patient cohort. We have noted sexual dimorphism in the MSC population and are pursuing this aspect in a separate study.
The translational goal of the laboratory is to use the knowledge from our basic science studies for tissue engineering, aimed at developing cell-based implants for repairing skeletal tissues compromised or destroyed by disease or injury. Our current work toward this goal includes developing novel bioresponsive, biodegradable scaffolds for use with stem cells to create implants that can be injected and polymerized in sites of cartilage and bone pathology.
In other work with scaffolds, the Johnstone lab is exploring alternative formulations for demineralized bone matrix implants for use in spinal fusion surgery. These implants contain many bioactive factors that stimulate local stem cells to differentiate into cartilage and bone. These implants will potentially reduce patients’ dependence on bone harvested from other sites in the body.
Choi Y, Oldenburg FP, Sage L, Johnstone B, Yoo JU. A bridging demineralized bone implant facilitates posterolateral lumbar fusion in New Zealand White Rabbits. Spine (2007) 32:36-41.
Buxton A, Zhu J, Marchant R, West J, Yoo J, Johnstone B. Design and Characterization of Poly(ethylene glycol) Photopolymerizable Semi-Interpenetrating Networks for Chondrogenesis of Human Mesenchymal Stem Cells Tiss Eng (2007) 13:2549-60.
Varas L, Bryngelson Ohlsson L, Honeth G, Olsson A, Bengtsson T, Wiberg C, Bockermann R, Jarnum S, Richter J, Pennington D, Johnstone B, Lundgren-Akelund E, Kjellman C. The alpha10 intergrin expression is up-regulated on FGF-2 treated mesenchymal stem cells with improved chondrogenic differentiation capacity. Stem Cells Dev (2007) 16:965-78.
Angele P, Johnstone B, Kujat R, Zellner J, Nerlich M, Goldberg, VM, Yoo J. Stem cell based tissue engineering for meniscus repair. J Biomed Mater Res A (2008) 85:445-55.
McAlinden A*, Johnstone B*, Kollar J, Kazmi N, Hering T. Expression of two novel alternatively spliced COL2A1 isoforms during chondrocyte differentiation. Matrix Biol (2008) 27:254-66. *contributed equally.
Angele P, Müller R, Schumann D, Englert C, Zellner J, Johnstone B, Yoo J, Hammer J, Fierlbeck J, Angele MK, Nerlich M, Kujat R.Characterization of esterified hyaluronan-gelatin polymer composites suitable for chondrogenic differentiation of mesenchymal stem cells. J Biomed Mater Res A. (2009) 91 (2): 416-27.
Buxton AN, Bahney CS, Yoo J, Johnstone B. Temporal Exposure to Chondrogenic Factors Modulates Human Mesenchymal Stem Cell Chondrogensis in Hydrogels. Tissue Eng Part A. [Epub ahead of print]