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Updated: May 29, 2026
Ex utero Electroporation and Whole Hemisphere Explants: A Simple Experimental Method for Studies of Early Cortical Development
Published on: April 3, 2013
Strain-dependent variation in the early transcriptional response to CNS injury using a cortical explant system
David J Graber1, Brent T Harris, William F Hickey
1Dept, Pathology, Dartmouth Medical School, Lebanon, New Hampshire, USA. David.J.Graber@Dartmouth.Edu
Background:
While it is clear that inbred strains of mice have variations in immunological responsiveness, the influence of genetic background following tissue damage in the central nervous system is not fully understood. A cortical explant system was employed as a model for injury to determine whether the immediate transcriptional response to tissue resection revealed differences among three mouse strains.
Methods:
Immunological mRNAs were measured in cerebral cortex from SJL/J, C57BL/6J, and BALB/cJ mice using real time RT-PCR. Freshly isolated cortical tissue and cortical sections incubated in explant medium were examined. Levels of mRNA, normalized to β-actin, were compared using one way analysis of variance with pooled samples from each mouse strain.
Results:
In freshly isolated cerebral cortex, transcript levels of many pro-inflammatory mediators were not significantly different among the strains or too low for comparison. Constitutive, baseline amounts of CD74 and antisecretory factor (ASF) mRNAs, however, were higher in SJL/J and C57BL/6J, respectively. When sections of cortical tissue were incubated in explant medium, increased message for a number of pro-inflammatory cytokines and chemokines occurred within five hours. Message for chemokines, IL-1α, and COX-2 transcripts were higher in C57BL/6J cortical explants relative to SJL/J and BALB/cJ. IL-1β, IL-12/23 p40, and TNF-α were lower in BALB/cJ explants relative to SJL/J and C57BL/6J. Similar to observations in freshly isolated cortex, CD74 mRNA remained higher in SJL/J explants. The ASF mRNA in SJL/J explants, however, was now lower than levels in both C57BL/6J and BALB/cJ explants.
Conclusions:
The short-term cortical explant model employed in this study provides a basic approach to evaluate an early transcriptional response to neurological damage, and can identify expression differences in genes that are influenced by genetic background.
Insights
Genetic background influences the central nervous system's transcriptional response to injury. Mouse strain differences in gene expression were observed in cortical explants following tissue damage, highlighting genetic impact on neurological responses.
Area of Science:
- Neuroscience
- Immunology
- Genetics
Background:
- Inbred mouse strains exhibit immunological variations.
- The impact of genetic background on central nervous system (CNS) tissue damage response is not fully understood.
- A cortical explant model was used to study immediate transcriptional responses to CNS injury.
Purpose of the Study:
- To investigate whether the immediate transcriptional response to tissue resection reveals genetic differences among three mouse strains.
- To determine the influence of genetic background on the early molecular events following CNS tissue damage.
Main Methods:
- Real-time RT-PCR was used to measure immunological mRNAs in cerebral cortex of SJL/J, C57BL/6J, and BALB/cJ mice.
- Cortical tissue sections were examined both freshly isolated and after incubation in explant medium.
- mRNA levels were normalized to β-actin and compared using one-way ANOVA.
Main Results:
- Baseline levels of CD74 and antisecretory factor (ASF) mRNAs differed among strains in freshly isolated tissue.
- Within five hours of incubation, pro-inflammatory cytokines and chemokines increased in cortical explants.
- Specific cytokine and chemokine transcript levels (e.g., IL-1α, COX-2, IL-1β, TNF-α) varied significantly among the mouse strains.
Conclusions:
- The short-term cortical explant model effectively reveals early transcriptional responses to neurological damage.
- This model can identify gene expression differences influenced by genetic background in the CNS.
- Genetic background plays a significant role in the immediate transcriptional response to CNS tissue injury.
