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Magnetic Resonance Imaging Allows the Evaluation of Tissue Damage and Regeneration in a Mouse Model of Critical Limb Ischemia.

Zaccagnini G, Palmisano A, Canu T, Maimone B, Lo Russo FM, Ambrogi F, Gaetano C, De Cobelli F, Del Maschio A, Esposito A, Martelli F - PLoS ONE (2015)

Bottom Line: Interestingly, K-trans positively correlated with capillary density.Overall, Gastrocnemius and Tibialis anterior muscles displayed similar patterns of MRI parameters dynamic, with more marked responses and less variability in Tibialis anterior.We conclude that MRI provides quantitative information about both tissue damage after ischemia and the subsequent vascular and muscle regeneration, accounting for the differences between subjects and, within the same individual, between different muscles.

View Article: PubMed Central - PubMed

Affiliation: Molecular Cardiology Laboratory, IRCCS-Policlinico San Donato, San Donato Milanese, Milan, Italy.

ABSTRACT
Magnetic resonance imaging (MRI) provides non-invasive, repetitive measures in the same individual, allowing the study of a physio-pathological event over time. In this study, we tested the performance of 7 Tesla multi-parametric MRI to monitor the dynamic changes of mouse skeletal muscle injury and regeneration upon acute ischemia induced by femoral artery dissection. T2-mapping (T2 relaxation time), diffusion-tensor imaging (Fractional Anisotropy) and perfusion by Dynamic Contrast-Enhanced MRI (K-trans) were measured and imaging results were correlated with histological morphometric analysis in both Gastrocnemius and Tibialis anterior muscles. We found that tissue damage positively correlated with T2-relaxation time, while myofiber regeneration and capillary density positively correlated with Fractional Anisotropy. Interestingly, K-trans positively correlated with capillary density. Accordingly, repeated MRI measurements between day 1 and day 28 after surgery in ischemic muscles showed that: 1) T2-relaxation time rapidly increased upon ischemia and then gradually declined, returning almost to basal level in the last phases of the regeneration process; 2) Fractional Anisotropy dropped upon ischemic damage induction and then recovered along with muscle regeneration and neoangiogenesis; 3) K-trans reached a minimum upon ischemia, then progressively recovered. Overall, Gastrocnemius and Tibialis anterior muscles displayed similar patterns of MRI parameters dynamic, with more marked responses and less variability in Tibialis anterior. We conclude that MRI provides quantitative information about both tissue damage after ischemia and the subsequent vascular and muscle regeneration, accounting for the differences between subjects and, within the same individual, between different muscles.

No MeSH data available.


Related in: MedlinePlus

Muscle histological analysis of low-responding, ischemia resistant mice.Representative Hematoxilin/Eosin stained sections of both Gastrocnemius (top) and Tibialis anterior (bottom) muscles of mice m513, m588 and m593 at day 21 (m513) and 28 (m588 and m593) after ischemia. Calibration bar = 100 μm. Black asterisks indicate healthy myofibers with peripheral nuclei. Blue asterisks indicates adipose cells. Black arrows indicate regenerating myofibers characterized by the central nuclei.
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pone.0142111.g007: Muscle histological analysis of low-responding, ischemia resistant mice.Representative Hematoxilin/Eosin stained sections of both Gastrocnemius (top) and Tibialis anterior (bottom) muscles of mice m513, m588 and m593 at day 21 (m513) and 28 (m588 and m593) after ischemia. Calibration bar = 100 μm. Black asterisks indicate healthy myofibers with peripheral nuclei. Blue asterisks indicates adipose cells. Black arrows indicate regenerating myofibers characterized by the central nuclei.

Mentions: To further investigate the different response of Gastrocnemius and Tibialis anterior muscles, we compared the dynamic trend of MRI parameters in each mouse. Interestingly we found that 3 mice out of 11 displayed an atypical, “low-response”, ischemic resistant phenotype, despite the surgery was carried out successfully, as assessed by MRA (S4 Fig). Mice m588 and m593 showed very similar T2-rt and FA parameters in the ischemic and in the controlateral Gastrocnemius muscles throughout the time course after femoral artery dissection (Fig 6A and 6B). On the contrary, these parameters measured in the Tibialis anterior muscle of the same limb, were altered as expected. When Hematoxilin/Eosin stained sections were analyzed at the end of the time course (Fig 7), important differences in the morphometric parameters were observed (Table 3). In particular, in keeping with the flat T2-rt curve, Gastrocnemius muscles did not show necrosis or tissue damage. Likewise, in agreement with the minimal changes observed in FA over time, only few regenerating myofibers were present in a globally healthy tissue. On the contrary, Tibialis anterior muscles displayed the expected post-ischemic pattern, with high percentage of regenerating myofibers and low adipose tissue substitution. Intriguingly, both Gastrocnemius and Tibialis anterior muscles displayed decreased capillary density (Table 3).


Magnetic Resonance Imaging Allows the Evaluation of Tissue Damage and Regeneration in a Mouse Model of Critical Limb Ischemia.

Zaccagnini G, Palmisano A, Canu T, Maimone B, Lo Russo FM, Ambrogi F, Gaetano C, De Cobelli F, Del Maschio A, Esposito A, Martelli F - PLoS ONE (2015)

Muscle histological analysis of low-responding, ischemia resistant mice.Representative Hematoxilin/Eosin stained sections of both Gastrocnemius (top) and Tibialis anterior (bottom) muscles of mice m513, m588 and m593 at day 21 (m513) and 28 (m588 and m593) after ischemia. Calibration bar = 100 μm. Black asterisks indicate healthy myofibers with peripheral nuclei. Blue asterisks indicates adipose cells. Black arrows indicate regenerating myofibers characterized by the central nuclei.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4640853&req=5

pone.0142111.g007: Muscle histological analysis of low-responding, ischemia resistant mice.Representative Hematoxilin/Eosin stained sections of both Gastrocnemius (top) and Tibialis anterior (bottom) muscles of mice m513, m588 and m593 at day 21 (m513) and 28 (m588 and m593) after ischemia. Calibration bar = 100 μm. Black asterisks indicate healthy myofibers with peripheral nuclei. Blue asterisks indicates adipose cells. Black arrows indicate regenerating myofibers characterized by the central nuclei.
Mentions: To further investigate the different response of Gastrocnemius and Tibialis anterior muscles, we compared the dynamic trend of MRI parameters in each mouse. Interestingly we found that 3 mice out of 11 displayed an atypical, “low-response”, ischemic resistant phenotype, despite the surgery was carried out successfully, as assessed by MRA (S4 Fig). Mice m588 and m593 showed very similar T2-rt and FA parameters in the ischemic and in the controlateral Gastrocnemius muscles throughout the time course after femoral artery dissection (Fig 6A and 6B). On the contrary, these parameters measured in the Tibialis anterior muscle of the same limb, were altered as expected. When Hematoxilin/Eosin stained sections were analyzed at the end of the time course (Fig 7), important differences in the morphometric parameters were observed (Table 3). In particular, in keeping with the flat T2-rt curve, Gastrocnemius muscles did not show necrosis or tissue damage. Likewise, in agreement with the minimal changes observed in FA over time, only few regenerating myofibers were present in a globally healthy tissue. On the contrary, Tibialis anterior muscles displayed the expected post-ischemic pattern, with high percentage of regenerating myofibers and low adipose tissue substitution. Intriguingly, both Gastrocnemius and Tibialis anterior muscles displayed decreased capillary density (Table 3).

Bottom Line: Interestingly, K-trans positively correlated with capillary density.Overall, Gastrocnemius and Tibialis anterior muscles displayed similar patterns of MRI parameters dynamic, with more marked responses and less variability in Tibialis anterior.We conclude that MRI provides quantitative information about both tissue damage after ischemia and the subsequent vascular and muscle regeneration, accounting for the differences between subjects and, within the same individual, between different muscles.

View Article: PubMed Central - PubMed

Affiliation: Molecular Cardiology Laboratory, IRCCS-Policlinico San Donato, San Donato Milanese, Milan, Italy.

ABSTRACT
Magnetic resonance imaging (MRI) provides non-invasive, repetitive measures in the same individual, allowing the study of a physio-pathological event over time. In this study, we tested the performance of 7 Tesla multi-parametric MRI to monitor the dynamic changes of mouse skeletal muscle injury and regeneration upon acute ischemia induced by femoral artery dissection. T2-mapping (T2 relaxation time), diffusion-tensor imaging (Fractional Anisotropy) and perfusion by Dynamic Contrast-Enhanced MRI (K-trans) were measured and imaging results were correlated with histological morphometric analysis in both Gastrocnemius and Tibialis anterior muscles. We found that tissue damage positively correlated with T2-relaxation time, while myofiber regeneration and capillary density positively correlated with Fractional Anisotropy. Interestingly, K-trans positively correlated with capillary density. Accordingly, repeated MRI measurements between day 1 and day 28 after surgery in ischemic muscles showed that: 1) T2-relaxation time rapidly increased upon ischemia and then gradually declined, returning almost to basal level in the last phases of the regeneration process; 2) Fractional Anisotropy dropped upon ischemic damage induction and then recovered along with muscle regeneration and neoangiogenesis; 3) K-trans reached a minimum upon ischemia, then progressively recovered. Overall, Gastrocnemius and Tibialis anterior muscles displayed similar patterns of MRI parameters dynamic, with more marked responses and less variability in Tibialis anterior. We conclude that MRI provides quantitative information about both tissue damage after ischemia and the subsequent vascular and muscle regeneration, accounting for the differences between subjects and, within the same individual, between different muscles.

No MeSH data available.


Related in: MedlinePlus