Homozygosity for the hemoglobin (Hb) S mutation (HbSS, sickle cell anemia) results in hemoglobin polymerization under hypoxic conditions leading to vaso-occlusion and hemolysis. Sickle cell anemia affects 1:500 African Americans and is a strong risk factor for kidney disease, although the mechanisms are not well understood. Heterozygous inheritance (HbAS; sickle cell trait) affects 1:10 African Americans and is associated with an increased risk for kidney disease in some reports. Using transgenic sickle mice, we investigated the histopathologic, ultrastructural, and gene expression differences with the HbS mutation. Consistent with progressive glomerular damage, we observed progressively greater urine protein concentrations (P = 0.03), glomerular hypertrophy (P = 0.002), and glomerular cellularity (P = 0.01) in HbAA, HbAS, and HbSS mice, respectively. Ultrastructural studies demonstrated progressive podocyte foot process effacement, glomerular basement membrane thickening with reduplication, and tubular villous atrophy with the HbS mutation. Gene expression studies highlighted the differential expression of several genes involved in prostaglandin metabolism (AKR1C18), heme and iron metabolism (HbA-A2, HMOX1, SCL25A37), electrolyte balance (SLC4A1, AQP6), immunity (RSAD2, C3, UBE2O), fatty acid metabolism (FASN), hypoxia hall-mark genes (GCK, SDC3, VEGFA, ETS1, CP, BCL2), as well as genes implicated in other forms of kidney disease (PODXL, ELMO1, FRMD3, MYH9, APOA1). Pathway analysis highlighted increased gene enrichment in focal adhesion, extracellular matrix-receptor interaction, and axon guidance pathways. In summary, using transgenic sickle mice, we observed that inheritance of the HbS mutation is associated with glomerular and tubular damage and identified several candidate genes and pathways for future investigation in sickle cell trait and sickle cell anemia-related kidney disease.
Key Points A reduction in hemolysis with voxelotor analog, GBT1118, reduced hemoglobinuria and kidney injury biomarkers in transgenic sickle mice. Improved chronic hemolysis preserved kidney function and histopathologic and ultrastructural changes in transgenic sickle mice.
Background: Technologies related to the establishment of primary tumor cell cultures from solid tumors, including glioblastoma, are increasingly important to oncology research and practice. However, processing of fresh tumor specimens for establishment of primary cultures on the day of surgical collection is logistically difficult. The feasibility of viable cryopreservation of glioblastoma specimens, allowing for primary culture establishment weeks to months after surgical tumor collection and freezing, was demonstrated by Mullins et al. in 2013, with a success rate of 59% that was not significantly lower than that achieved with fresh tumor tissue. However, research targeting optimization of viable glioblastoma cryopreservation protocols for establishment of primary tumor cultures has been limited. Objectives: The objective of this study was to optimize glioblastoma cryopreservation methods for viable cryobanking and to determine if two-dimensional (2D) or three-dimensional (3D) culture conditions were more supportive of glioblastoma growth after thawing of frozen tumor specimens. Methods: Portions of eight human glioblastoma specimens were cryopreserved by four different protocols differing in the time of enzymatic digestion (before or after cryopreservation), and in the type of cryopreservation media (CryoStor CS10 or 10% dimethyl sulfoxide and 90% fetal calf serum). After 1 month, frozen tissues were thawed, enzymatically digested, if not digested before, and used for initiation of 2D or 3D primary tumor cultures to determine viability. Results: Among the tested cryopreservation and culturing protocols, the most efficient combinations of cryopreservation and culture were those associated with the use of CryoStor CS10 cryopreservation medium, enzymatic digestion before freezing, and 2D culturing after thawing with a successful culture rate of 8 out of 8 cases (100%). Two-dimensional cultures were in general more efficient for the support of tumor cell growth after thawing than 3D cultures. Conclusions: This study supports development of evidence-based viable glioblastoma cryopreservation methods for use in glioblastoma biobanking and research.
Homozygous inheritance of the hemoglobin S mutation (Hb SS; sickle cell anemia) affects 1 in 500 African Americans and is consistently associated with an increased risk for kidney disease, although the mechanisms are poorly understood. Heterozygous inheritance (Hb AS; sickle cell trait) affects 1 in 8 African Americans and has also been associated with an increased risk for kidney disease in some, but not all cohorts. We first investigated whether inheritance of the Hb S mutation resulted in incremental kidney damage in Hb AS and Hb SS mice compared to Hb AA mice using transgenic sickle mice >6 months old (Townes model, Jackson Laboratory). Using Masson trichrome stained sections of the kidney, patterns of mesangial expansion were determined in age- and sex-matched mice by a renal pathologist blinded to the hemoglobin genotype of each specimen. Hb AS mice had diffuse (>50% of the glomeruli per slide being involved) mesangial expansion while Hb SS mice had diffuse and global (>50% of the individual glomerulus being involved) mesangial expansion. Glomerular perimeters were measured using NanoZoomer Whole Slide Imaging in 26 randomly selected glomeruli from 2 mice per genotype. Using >300µm in circumference as the definition for an enlarged glomerulus, the proportion of enlarged glomeruli progressively increased from Hb AA to Hb AS to Hb SS mice (Cochran's test of linear trend, P=0.002)(Figure 1A). Progressively higher urine protein-to-creatinine ratios were also observed from Hb AA to Hb AS to Hb SS mice (Figure 1B; test for linear trend, P=0.03) as were progressively higher kidney weights: Hb AA (429±28mg, n=8), Hb AS (446±27mg, n=18), Hb SS (567±19mg, n=5) (Test for linear trend, P=0.047). We then compared the mRNA expression profiles in the kidney cortices, which predominantly include glomerular and proximal tubular cells, of 15 age- and sex-matched mice (5 per Hb genotype) using the Affymetrix Mouse Gene 2.0ST Array. Using an additive model with an FDR<0.01, 6 of the 10 most differentially expressed genes were involved in heme or iron metabolism (HMOX1: β 0.93, P=0.0004; SLC25A37: β 0.75, P=3.9x10-6), kidney function (SLC4A1: β 0.87, P=1.0x10-5; AQP6: β 0.79, P=2.0x10-5), or inflammation (RSAD2: β 0.76, P=5.2x10-6; C3: β 0.76, P=0.0005). Other genes that have been implicated in kidney disease and were differentially expressed at an FDR<0.01 included PODXL and EFNB2 (encode glomerular proteins integral for maintaining the filtration barrier) as well as FRMD3 and ELMO1 (implicated in diabetic nephropathy). KEGG physiologic pathways among the differentially expressed genes included focal adhesion (3.4-fold, P=6.0x10-7), extracellular matrix-receptor interaction (5.0-fold, P=3.2x10-6), and phosphatidylinositol signaling systems (3.5-fold, P=0.003). In conclusion, we observed progressive glomerular injury, determined by mesangial expansion, proportion of enlarged glomeruli, and urine protein concentrations, in Hb AS and Hb SS mice compared to Hb AA mice. Renal cortex-expressed genes involved in heme and iron homeostasis, kidney function, and inflammation were differentially expressed with inheritance of the Hb S mutation and may play important roles in the pathophysiology of kidney disease in individuals with sickle cell trait or sickle cell disease and will require further investigation. Figure Figure. Disclosures No relevant conflicts of interest to declare.
The hemoglobin S mutation, a glutamic acid to valine substitution in the β-globin chain, results in hemoglobin polymerization under hypoxic conditions and leads to vaso-occlusion and hemolysis. Homozygous inheritance (Hb SS; sickle cell anemia) affects 1 in 500 African Americans and is consistently associated with an increased risk for kidney disease which may be due to cell-free hemoglobin toxicity, ischemic injury, or hyperfiltration-mediated damage to the kidney. Heterozygous inheritance (Hb AS; sickle cell trait) affects 1 in 8 African Americans and has also been associated with an increased risk for kidney disease, although not in all cohorts and the mechanisms are not well understood.We investigated whether inheritance of the Hb S mutation resulted in incremental kidney damage in Hb AS and Hb SS mice compared to Hb AA mice by histology, proteinuria, and candidate gene expression using transgenic sickle mice ≥6 months of age (Townes model, Jackson Laboratory). Values are presented as mean±standard error and analyses are adjusted for age.Using Masson trichrome stained sections of the kidney, progressive patterns of mesangial expansion were observed in age-matched Hb AS and Hb SS mice versus Hb AA mice by renal pathologists blinded to the hemoglobin genotype (figure 1). Hb AS mice had diffuse (>50% of the glomeruli per slide being involved) mesangial expansion while Hb SS mice had diffuse and global (>50% of the individual glomerulus being involved) mesangial expansion. Glomerular perimeters were measured using NanoZoomer Whole Slide Imaging in 26 randomly selected glomeruli from 2 age-matched mice per genotype. Using the upper quartile as the definition for an enlarged glomerulus, the proportion of enlarged glomeruli progressively increased from Hb AA (15%) to Hb AS (31%) to Hb SS mice (58%) (Cochran's test of linear trend, P=0.001) (figure 2). Progressively higher kidney weights were also observed from Hb AA (429±28 mg, n=8) to Hb AS (446±27 mg, n=18) to Hb SS (567±19 mg, n=5) mice (Test for linear trend, P=0.047). We then measured urine protein and urine creatinine concentrations using the Bio-Rad dye method and Jaffé reaction, respectively. Progressively higher urine protein-to-creatinine ratios were observed from Hb AA to Hb AS to Hb SS mice (figure 3) (Test for linear trend, P=0.09). Gene expression of candidate genes (TGFB1, IL6, MMP9, Klotho, HMOX1, and SHROOM3) was determined by rt-PCR from kidneys of age-matched, female Hb AA and Hb AS mice (n=5). Increased expression of Klotho (P=0.09) was observed in Hb AS mice (figure 4). Klotho is a β-glucoronidase that is highly expressed in the kidney and acts as a cofactor that increases the affinity of the FGF23 ligand for the FGF receptor.In conclusion, we observed progressive glomerular injury, determined by mesangial expansion, proportion of enlarged glomeruli, and urine protein concentrations in Hb AS and Hb SS mice compared to Hb AA mice. Klotho was upregulated in Hb AS mice and may play a role in the pathophysiology of kidney damage in Hb AS which will r...
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