Gene-expression analysis of single cells-nested polymerase chain reaction after laser microdissection

Fusion of Wild-Type Mesoangioblasts with Myotubes of mtDNA Mutation Carriers Leads to a Proportional Reduction in mtDNA Mutation Load

In 25% of patients with mitochondrial myopathies, pathogenic mitochondrial DNA (mtDNA) mutation are the cause. For heteroplasmic mtDNA mutations, symptoms manifest when the mutation load exceeds a tissue-specific threshold. Therefore, lowering the mutation load is expected to ameliorate disease manifestations. This can be achieved by fusing wild-type mesoangioblasts with mtDNA mutant myotubes. We have tested this in vitro for female carriers of the m.3271T>C or m.3291T>C mutation (mutation load >90%) using wild-type male mesoangioblasts. Individual fused myotubes were collected by a newly-developed laser capture microdissection (LCM) protocol, visualized by immunostaining using an anti-myosin antibody. Fusion rates were determined based on male-female nuclei ratios by fluorescently labelling the Y-chromosome. Using combined 'wet' and 'air dried' LCM imaging improved fluorescence imaging quality and cell yield. Wild-type mesoangioblasts fused in different ratios with myotubes containing either the m.3271T>C or the m.3291T>C mutation. This resulted in the reduction of the mtDNA mutation load proportional to the number of fused wild-type mesoangioblasts for both mtDNA mutations. The proportional reduction in mtDNA mutation load in vitro after fusion is promising in the context of muscle stem cell therapy for mtDNA mutation carriers in vivo, in which we propose the same strategy using autologous wild-type mesoangioblasts.

Human papillomavirus infection status of single cells isolated from cervical cytology specimens by simple manual microdissection

Human papillomavirus (HPV) testing with cytology triage for cervical cancer screening has proven to be useful. It is considered that a significant percentage of HPV-positive women followed by reflex cytology have had multiple-type HPV infections rather than single-type infections. However, the effects of multiple-type infections on changes in the cytomorphology of exfoliated cervical cells have not been investigated. The aim of this study was to validate simple manual microdissection (MMD) maneuver and investigate the HPV infection status of single cells isolated from Papanicolaou (Pap) smears prepared from women with multiple-type infections. Using cytology samples from 90 patients with abnormal Pap smear results, we evaluated the efficiency of the MMD procedure and determined the HPV infection status of single squamous intraepithelial lesion (SIL) cells microdissected from patients with multiple-type infection. When validating the MMD procedure, the HPV-positive rate was 81.5% using 119 MMD samples from the Pap smear in 61 cases with single-type infection. This MMD procedure was able to efficiently collect single cells. Of 119 MMD samples from 29 cases with multiple-type infection, the HPV-positive rate was 42.9%, and most (96.1%) MMD samples exhibited only one genotype. Our MMD maneuver successfully identified HPV genotypes using single cells isolated from cytology specimens. A majority of single SIL cells prepared from multiple-type infection cases turned out to contain only one genotype. In the future, the MMD method could be applied while studying the relationship between the morphological changes exhibited by SIL cells on Pap smear and the infected HPV genotype.

Laser microdissection-based analysis of cytokine balance in the kidneys of patients with lupus nephritis

To determine the cytokine balance in patients with lupus nephritis (LN), we analysed kidney-infiltrating T cells. Renal biopsy samples from 15 systemic lupus erythematosus (SLE) patients were used. In accordance with the classification of International Society of Nephrology/Renal Pathology Society, they were categorized into Class III, Class III+V (Class III-predominant group, n = 4), Class IV, Class IV+V (Class IV-predominant group, n = 7) and Class V (n = 4) groups. The single-cell samples of both the glomelular and interstitial infiltrating cells were captured by laser-microdissection. The glomerular and interstitial infiltrating T cells produced interleukin (IL)-2, IL-4, IL-10, IL-13 and IL-17 cytokines in the Class III-predominant, Class IV-predominant and Class V groups. Interferon-gamma was detected only in the glomeruli of the Class III-predominant and Class V group samples. The expression level of IL-17 was correlated closely with clinical parameters such as haematuria, blood urea nitrogen level, SLE Disease Activity Index scores in both glomeruli and interstitium, urine protein level in glomeruli and serum creatinine and creatinine clearance levels in interstitium. This suggests that the glomerular infiltrating T cells might act as T helper type 1 (Th1), Th2 and Th17 cells while the interstitial infiltrating T cells, act as Th2 and Th17 cells in the Class III-predominant and Class V groups. In contrast, both the glomerular and interstitial infiltrating T cells might act as Th2 and Th17 cells in the Class IV-predominant group. The cytokine balances may be dependent upon the classification of renal pathology, and IL-17 might play a critical role in SLE development.

Combining laser capture microdissection with quantitative real-time PCR: effects of tissue manipulation on RNA quality and gene expression

Laser capture microdissection (LCM) is increasingly being used in quantitative gene expression studies of the nervous system. The current study aimed at determining the impact of various tissue manipulations on the integrity of extracted RNA in LCM studies. Our data indicate that various tissue preparation strategies prior to microdissection may decrease RNA quality by as much as 25%, thus affecting expression profiles of some genes. To circumvent this problem, we developed a strategy for reverse transcriptase real-time PCR that has considerable sensitivity and can be used to calculate relative changes in gene expression. This approach was validated in subregions of the rat cerebellum. Accordingly, expression of glial gene markers - myelin-associated glycoprotein and proteolipid protein 1 - was found 70-160-fold higher in the white matter layer of the cerebellar cortex as compared to the neuron-enriched granular layer. In contrast, expression of a specific neuronal maker, neuron-specific enolase, was found seven-fold higher in the granular layer, as compared to the white matter layer. Furthermore, this approach had high sensitivity and specificity as we were able to detect a 38% decrease in the expression of neuron-specific enolase without a change in the expression of glial markers following administration of the neurotoxin, ibotenic acid. These results demonstrate feasibility of performing accurate semi-quantitative gene expression analyses in LCM samples.