The frequency of chronic renal failure increases with age, especially in women after menopause. Glomerulosclerosis is a common cause of chronic renal failure in aging. We reported that pre-menopausal female C57BL6 (B6) mice are resistant to glomerulosclerosis, irrespective of the type of injury. However, we now show that B6 mice develop progressive glomerulosclerosis after menopause. Glomerular lesions, first recognized in 18-month-old mice, consisted of hypertrophy, vascular pole sclerosis, and mesangial cell proliferation. Diffuse but moderate mesangial sclerosis and more marked hypertrophy were present at 22 months. At 28 to 30 months the glomerulosclerosis was diffuse and increased levels of type I and type IV collagen and transforming growth factor-␤1 mRNA were present. Urine albumin excretion was significantly increased in 30-month-old mice. Chronic renal failure is a major health problem world-wide and its prevalence has been rising.

We found that ROP Os/+ (Os/+) mice had diffuse glomerulosclerosis and glomerular hypertrophy and that their mesangial cells (the vascular smooth muscle cells of the glomerulus) displayed an apparent sclerosing phenotype. Since mesangial cells are the major source of scar tissue in glomerulosclerosis, we postulated that the sclerosis phenotype was carried by mesangial cell progenitors and that this phenotype could be derived from the bone marrow (BM). Therefore, we transplanted BM from Os/+ mice into congenic ROP +/+ mice (+/+ mice), which have normal glomeruli. We found that glomeruli of +/+ recipients of Os/+ marrow contained the Os/+ genotype, were hypertrophied, and contained increased extracellular matrix. Clones of recipient glomerular mesangial cells with the donor genotype were found in all +/+ recipients that developed mesangial sclerosis and glomerular hypertrophy, whereas +/+ recipients of +/+ BM had normal glomeruli. Thus, the sclerotic (Os/+) or normal (+/+) genotype and phenotype were present in, and transmitted by, BM-derived progenitors. These data show that glomerular mesangial cell progenitors are derived from the BM and can deliver a disease phenotype to normal glomeruli. Glomerular lesions may therefore be perpetuated or aggravated, rather than resolved, by newly arriving progenitor cells exhibiting a disease phenotype.

The accumulation of advanced glycation end products (AGE) is a key factor in diabetic nephropathy (DN). Pyridoxamine inhibits AGE formation and protects against type I DN. Herein we tested: (1) whether C57BL6 db/db mice as a model of established type II DN resembled patients treated with drugs which inhibit angiotensin II action; (2) whether pyridoxamine was effective as a single therapy; and (3) whether pyridoxamine would add to the benefit of angiotensin-converting enzyme inhibition (ACEi) by enalapril. In first set of experiments mice were treated with ACEi (benazepril) and an angiotensin II receptor blocker (valsartan) combination for 16 weeks after the onset of diabetes. In second group, mice with established DN were treated with pyridoxamine for 8 weeks. In a third set, mice with established DN were treated with pyridoxamine and enalapril combination for 16 weeks. Benazepril and valsartan combination partially prevented the development and progression of DN. Pyridoxamine treatment, as single therapy, decreased the progression of albuminuria and glomerular lesions. The combination of pyridoxamine with enalapril reduced both mortality and the progression of DN. In conclusion, (1) C57 BL6 db/db mice are a model of progressive type II DN; (2) The combination of pyridoxamine with enalapril decreased progression of type 2 DN and overall mortality. Thus, pyridoxamine could be a valuable adjunct to the current treatment of established type II DN.

The pathologic hallmarks of diabetic nephropathy are excess mesangial extracellular matrix (ECM) and mesangial cell proliferation. We previously showed that mesangial cell phenotypic changes play an important role in the pathogenesis of diabetic nephropathy. We concluded that phenotypic changes were present in bone marrow (BM)-derived mesangial cell progenitors, as transplantation of BM from db/db mice, a model of type 2 diabetic nephropathy, transferred the db genotype and a nephropathy phenotype to naive B6 mice recipients. The recipients did not develop diabetes; however, they did develop albuminuria and glomerular lesions mirroring those in the donors (i.e., glomerular hypertrophy, increased ECM, and increased cell number with cell proliferation). We found that matrix metalloproteinase 2 (MMP-2) facilitated invasion of the mesangial cells into ECM and proliferation in vitro. Thus, increased MMP-2 activity in db/db mesangial cell progenitors may partially explain increased mesangial cell repopulation and proliferation in B6 recipients of db/db BM. In summary, BM-derived mesangial cell progenitors may play a crucial role in the development and progression of ECM accumulation and mesangial cell proliferation in this model of diabetic nephropathy in type 2 diabetes.

Here we report the case of successful immune tolerance induction in a living‐donor kidney transplant recipient remotely treated with autologous bone marrow‐derived mesenchymal stromal cells (MSC). This case report, which to the best of our knowledge is the first in the world in this setting, provides evidence that the modulation of the host immune system with MSC can enable the safe withdrawal of maintenance immunosuppressive drugs while preserving optimal long‐term kidney allograft function.