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The global prevalence of kidney diseases has been steadily rising over the last decades. Today, around 10% of the world population suffers from relevant chronic kidney disease. Podocytes are highly specialized and terminally differentiated cells residing in the filtering units of the kidneys, the so-called glomeruli. With their interdigitating foot-processes, these cells are a crucial part of the renal filtration barrier. As podocytes are post-mitotic, injury or loss of these cells results in an impairment of the filtration barrier with subsequent loss of global kidney function. Therefore, the question whether a relevant amount of podocytes can be regenerated and if this regeneration can be influenced is crucial for future therapeutic developments. As in vivo microscopic imaging of podocytes in higher animals like mice or rats is rather challenging, larval zebrafish have been applied as an animal model for podocyte development and kidney filtration. 48 hours post fertilization, zebrafish larvae develop a single filtering glomerulus with a similar morphology and molecular construction to that in mammals. For evaluation of podocyte morphology and filtration, we used transgenic zebrafish strains in which podocytes were labeled with fluorescence proteins. Additionally, podocytes expressed the bacterial enzyme nitroreductase fused to the fluorescence protein mCherry. In this model, application of the antibiotic metronidazole leads to podocyte-specific cell death. Through cross-breeding we established strains that additionally express an eGFP-labeled protein in the blood plasma. Using in vivo two-photon microscopy, we could image podocyte-loss induced impairments of the glomerular filtration barrier. Additionally, we tracked characteristic morphological changes of podocyte morphology including podocyte foot process effacement, development of sub-podocyte pseudocysts and finally detachment of whole cells from the glomerular basement membrane. These changes have been before described histologically in different animal models as well as in patient biopsies. Using the in vivo microscopy approach, we could clearly describe the temporal sequence of these alterations. Finally, we also tracked individual, non-detached podocytes over up to 24 hours, and found that these cells were non-migratory. These results show that early podocyte-regeneration through immigration of intra- or extraglomerular cells is unlikely within the first 24 hours of acute glomerular injury.
The local anesthetic lidocaine, which has been used extensively during liposuction, has been
reported to have cytotoxic effects and therefore would be unsuitable for use in autologous lipotransfer.
We evaluated the effect of lidocaine on the distribution, number, and viability of adipose-derived stem
cells (ASCs), preadipocytes, mature adipocytes, and leukocytes in the fatty and fluid portion of the
lipoaspirate using antibody staining and flow cytometry analyses. Adipose tissue was harvested from
11 female patients who underwent liposuction. Abdominal subcutaneous fat tissue was infiltrated
with tumescent local anesthesia, containing lidocaine on the left and lacking lidocaine on the right
side of the abdomen, and harvested subsequently. Lidocaine had no influence on the relative
distribution, cell number, or viability of ASCs, preadipocytes, mature adipocytes, or leukocytes in the
stromal-vascular fraction. Assessing the fatty and fluid portions of the lipoaspirate, the fatty portions
contained significantly more ASCs (p < 0.05), stem cells expressing the preadipocyte marker Pref-1
(p < 0.01 w/lidocaine, p < 0.05 w/o lidocaine), and mature adipocytes (p < 0.05 w/lidocaine, p < 0.01
w/o lidocaine) than the fluid portions. Only the fatty portion should be used for transplantation. This
study found no evidence that would contraindicate the use of lidocaine in lipotransfer. Limitations of
the study include the small sample size and the inclusion of only female patients.