MANF Produced by MRL Mouse-Derived Mesenchymal Stem Cells Is Pro-regenerative and Protects From Osteoarthritis

PLOD2, a key factor for MRL MSC metabolism and chondroprotective properties

BACKGROUND

Initially discovered for its ability to regenerate ear holes, the Murphy Roth Large (MRL) mouse has been the subject of multiple research studies aimed at evaluating its ability to regenerate other body tissues and at deciphering the mechanisms underlying it. These enhanced abilities to regenerate, retained during adulthood, protect the MRL mouse from degenerative diseases such as osteoarthritis (OA). Here, we hypothesized that mesenchymal stromal/stem cells (MSC) derived from the regenerative MRL mouse could be involved in their regenerative potential through the release of pro-regenerative mediators.

METHOD

To address this hypothesis, we compared the secretome of MRL and BL6 MSC and identified several candidate molecules expressed at significantly higher levels by MRL MSC than by BL6 MSC. We selected one candidate, Plod2, and performed functional in vitro assays to evaluate its role on MRL MSC properties including metabolic profile, migration, and chondroprotective effects. To assess its contribution to MRL protection against OA, we used an experimental model for osteoarthritis induced by collagenase (CiOA).

RESULTS

Among the candidate molecules highly expressed by MRL MSC, we focused our attention on procollagen-lysine,2-oxoglutarate 5-dioxygenase 2 (PLOD2). Plod2 silencing induced a decrease in the glycolytic function of MRL MSC, resulting in the alteration of their migratory and chondroprotective abilities in vitro. In vivo, we showed that Plod2 silencing in MRL MSC significantly impaired their capacity to protect mouse from developing OA.

CONCLUSION

Our results demonstrate that the chondroprotective and therapeutic properties of MRL MSC in the CiOA experimental model are in part mediated by PLOD2.

Mesencephalic astrocyte-derived neurotrophic factor (MANF): Structure, functions and therapeutic potential

Mesencephalic astrocyte-derived neurotrophic factor (MANF) is a novel evolutionarily conserved protein present in both vertebrate and invertebrate species. MANF shows distinct structural and functional properties than the traditional neurotrophic factors (NTF). MANF is composed of an N-terminal saposin-like lipid-binding domain and a C-terminal SAF-A/B, Acinus and PIAS (SAP) domain connected by a short linker. The two well-described activities of MANF include (1) role as a neurotrophic factor that plays direct neuroprotective effects in the nervous system and (2) cell protective effects in the animal models of non-neuronal diseases, including retinal damage, diabetes mellitus, liver injury, myocardial infarction, nephrotic syndrome, etc. The main objective of the current review is to provide up-to-date insights regarding the structure of MANF, mechanisms regulating its expression and secretion, physiological functions in various tissues and organs, protective effects during aging, and potential clinical applications. Together, this review highlights the importance of MANF in reversing age-related dysfunction and geroprotection.

Pyrroline-5-Carboxylate Reductase 1 Directs the Cartilage Protective and Regenerative Potential of Murphy Roths Large Mouse Mesenchymal Stem Cells

Murphy Roths Large (MRL) mice possess outstanding capacity to regenerate several tissues. In the present study, we investigated whether this regenerative potential could be associated with the intrinsic particularities possessed by their mesenchymal stem cells (MSCs). We demonstrated that MSCs derived from MRL mice (MRL MSCs) display a superior chondrogenic potential than do C57BL/6 MSC (BL6 MSCs). This higher chondrogenic potential of MRL MSCs was associated with a higher expression level of pyrroline-5-carboxylate reductase 1 (PYCR1), an enzyme that catalyzes the biosynthesis of proline, in MRL MSCs compared with BL6 MSCs. The knockdown of PYCR1 in MRL MSCs, using a specific small interfering RNA (siRNA), abolishes their chondrogenic potential. Moreover, we showed that PYCR1 silencing in MRL MSCs induced a metabolic switch from glycolysis to oxidative phosphorylation. In two in vitro chondrocyte models that reproduce the main features of osteoarthritis (OA) chondrocytes including a downregulation of chondrocyte markers, a significant decrease of PYCR1 was observed. A downregulation of chondrocyte markers was also observed by silencing PYCR1 in freshly isolated healthy chondrocytes. Regarding MSC chondroprotective properties on chondrocytes with OA features, we showed that MSCs silenced for PYCR1 failed to protect chondrocytes from a reduced expression of anabolic markers, while MSCs overexpressing PYCR1 exhibited an increased chondroprotective potential. Finally, using the ear punch model, we demonstrated that MRL MSCs induced a regenerative response in non-regenerating BL6 mice, while BL6 and MRL MSCs deficient for PYCR1 did not. In conclusion, our results provide evidence that MRL mouse regenerative potential is, in part, attributed to its MSCs that exhibit higher PYCR1-dependent glycolytic potential, differentiation capacities, chondroprotective abilities, and regenerative potential than BL6 MSCs.