Tracking mesenchymal stem cell contributions to regeneration in an immunocompetent cartilage regeneration model
Daniela Zwolanek, María Satué, Verena Proell, José R. Godoy, Kathrin I. Odörfer, Magdalena Flicker, Sigrid C. Hoffmann, Thomas Rülicke, Reinhold G. Erben
Daniela Zwolanek, María Satué, Verena Proell, José R. Godoy, Kathrin I. Odörfer, Magdalena Flicker, Sigrid C. Hoffmann, Thomas Rülicke, Reinhold G. Erben
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Resource and Technical Advance Stem cells Transplantation

Tracking mesenchymal stem cell contributions to regeneration in an immunocompetent cartilage regeneration model

Abstract

It is currently controversially discussed whether mesenchymal stem cells (MSC) facilitate cartilage regeneration in vivo by a progenitor- or a nonprogenitor-mediated mechanism. Here, we describe a potentially novel unbiased in vivo cell tracking system based on transgenic donor and corresponding immunocompetent marker–tolerant recipient mouse and rat lines in inbred genetic backgrounds. Tolerance of recipients was achieved by transgenic expression of an immunologically neutral but physicochemically distinguishable variant of the marker human placental alkaline phosphatase (ALPP). In this dual transgenic system, donor lines ubiquitously express WT, heat-resistant ALPP protein, whereas recipient lines express a heat-labile ALPP mutant (ALPPE451G) resulting from a single amino acid substitution. Tolerance of recipient lines to ALPP-expressing cells and tissues was verified by skin transplantation. Using this model, we show that intraarticularly injected MSC contribute to regeneration of articular cartilage in full-thickness cartilage defects mainly via a nonprogenitor-mediated mechanism.

Authors

Daniela Zwolanek, María Satué, Verena Proell, José R. Godoy, Kathrin I. Odörfer, Magdalena Flicker, Sigrid C. Hoffmann, Thomas Rülicke, Reinhold G. Erben

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Figure 2

Histochemical ALPP staining and long-term tolerance of Tg(ALPPm) recipients to skin grafts from Tg(ALPP) donors.

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Histochemical ALPP staining and long-term tolerance of Tg(ALPPm) recipie...
(A) ALPP histochemistry on paraffin or plastic (bone and knee joint) sections from various organs of Tg(ALPP), Tg(ALPPm), and WT mice after a 35-minute heat inactivation at 72°C. Tg(ALPP) donors show strong staining in all tissues, whereas no enzyme activity could be detected in WT and Tg(ALPPm) mice. Scale bar: 50 μm. n = 10 per group. (B) Histochemistry of skin grafts from Tg(ALPP) at 3 and 24 weeks after transplantation. Strong ALPP staining was present in Tg(ALPP) grafts transplanted into Tg(ALPPm) recipients. Grafts from Tg(ALPP) mice were rejected by WT recipients, shown by the pronounced decline in ALPP staining within the grafts over time. Scale bar: 500 μm. n = 10 per group. (C) Leukocyte infiltration of skin grafts from Tg(ALPP) donor mice was quantified by CD45R immunostaining at 3 and 24 weeks after surgery and expressed as number of positive cells per tissue section. n ≥ 5 per group. (D) Histochemistry of skin grafts from Tg(ALPP) rats at 4 weeks after transplantation. Strong ALPP staining was present in Tg(ALPP) grafts transplanted into Tg(ALPPm) recipients. Grafts from Tg(ALPP) rats were rejected by WT recipients, as shown by the almost absent ALPP staining within the grafts. Scale bar: 500 μm. n = 10 per group. (E) Leukocyte infiltration of skin grafts from Tg(ALPP) donor rats was quantified by CD45 immunostaining at 4 weeks after transplantation and expressed as number of positive cells per tissue section. n ≥ 10 per group. *P < 0.05 by one-way ANOVA followed by Student-Newman-Keuls multiple comparison test. ALPP, human placental alkaline phosphatase; ALPPm, ALPPE451G mutant; ALPP → ALPPm, transplantation from Tg(ALPP) donor into Tg(ALPPm) recipient; TX, transplantation.