Evaluation of intrarenal mesenchymal stem cell injection for treatment of chronic kidney disease in cats: a pilot study

Abstract

The feasibility of autologous intrarenal mesenchymal stem cell (MSC) therapy in cats with chronic kidney disease (CKD) was investigated. Six cats (two healthy, four with CKD) received a single unilateral intrarenal injection of autologous bone marrow-derived or adipose tissue-derived MSC (bmMSC or aMSC) via ultrasound guidance. Minimum database and glomerular filtration rate (GFR) via nuclear scintigraphy were determined pre-injection, at 7 days and at 30 days post-injection. Intrarenal injection did not induce immediate or long-term adverse effects. Two cats with CKD that received aMSC experienced modest improvement in GFR and a mild decrease in serum creatinine concentration. Despite the possible benefits of intrarenal MSC injections for CKD cats, the number of sedations and interventions required to implement this approach would likely preclude widespread clinical application. We concluded that MSC could be transferred safely by ultrasound-guided intrarenal injection in cats, but that alternative sources and routes of MSC therapy should be investigated.

Fig 1.

Phenotype of feline aMSC in culture. Feline adipose-derived MSC were established from adipose tissue biopsies, as described in the materials and methods. Cells assumed a typical elongated morphology, as described previously for feline MSC. (Feline adipose MSC, magnification 10×.)

Fig 2.

Expression of cell surface markers by feline adipose-derived MSC. Primary cultures of feline MSC obtained from cats 3, 7 and 8 were passaged three to five times in culture, then collected by trypsinization and immunostained for assessment of cell surface marker expression by flow cytometry, as described in the materials and methods. Feline adipose MSC expressed high surface levels of CD44, CD90, and CD105 (panel A), but did not express CD4 or MHC class II (panel B). Isotype controls are represented in red and unstained MSC are represented in blue. Similar results were obtained with adipose MSC from two additional young healthy research cats (not described in this study).

Fig 3.

Trilineage differentiation of feline aMSC. (A) Control aMSC incubated in standard media stained with Oil red O. (B) aMSC produced intracellular lipid vacuoles when incubated in adipocytic differentiation media for 21 days. (C) Control aMSC incubated in standard media stained with Alizarin red. (D) aMSC stained positive for calcium with Alizarin red following differentiation into osteocytic phenotype after 21 days of incubation in differentiation media. (E) Cryosection of pellets of cartilage matrix (stained with toluidine blue) formed by aMSC when exposed to chondrocytic differentiation media for 21 days.

Fig 4.

Changes in GFR over time in cats with CKD that received unilateral intrarenal MSC injections. GFR via nuclear scintigraphy was evaluated prior to treatment, on day 7 and day 30 in three cats for the injected kidney (A) and non-injected kidney (B). Modest improvement in GFR in the injected kidney was seen in one cat. Mild improvement in GFR of both kidneys was seen in one cat. While GFR variability in non-treated cats was assessed to be approximately 9.6%, CKD cats 7 and 8 had global GFR increases of 16% and 55% from baseline, respectively.

Fig 5.

Changes in serum creatinine concentration over time in cats with CKD that received unilateral, intrarenal MSC injections. Serum creatinine concentrations were evaluated prior to treatment, on day 7, day 30 and on day 60 in two cats that completed a 60-day trial of MSC injection therapy. There was a 9.8% overall decline in mean serum creatinine at day 60 compared to pre-treatment value in the two cats.