Ai Namioka, Takahiro Namioka, Masanori Sasaki, Yuko Kataoka-Sasaki, Shinichi Oka, Masahito Nakazaki, Rie Onodera, Junpei Suzuki, Yuichi Sasaki, Hiroshi Nagahama, Jeffery D. Kocsis and Osamu Honmou
Morbidity and mortality in patients with posterior circulation stroke remains an issue despite advances in acute stroke therapies. The intravenous infusion of mesenchymal stem cells (MSCs) elicits therapeutic efficacy in experimental supratentorial stroke models. However, since there are few reliable animal models of ischemia in the posterior circulation, the therapeutic approach with intravenous MSC infusion has not been tested. The objective of this study was to test the hypothesis that intravenously infused MSCs provide functional recovery in a newly developed model of brainstem infarction in rats.
Basilar artery (BA) occlusion (BAO) was established in rats by selectively ligating 4 points of the proximal BA with 10-0 nylon monofilament suture. The intravenous infusion of MSCs was performed 1 day after BAO induction. MRI and histological examinations were performed to assess ischemic lesion volume, while multiple behavioral tests were performed to evaluate functional recovery.
The MSC-treated group exhibited a greater reduction in ischemic lesion volume, while behavioral testing indicated that the MSC-infused group had greater improvement than the vehicle group 28 days after the MSC infusion. Accumulated infused MSCs were observed in the ischemic brainstem lesion.
Infused MSCs may provide neuroprotection to facilitate functional outcomes and reduce ischemic lesion volume as evaluated in a newly developed rat model of persistent BAO.
Takahiro Namioka, Ai Namioka, Masanori Sasaki, Yuko Kataoka-Sasaki, Shinichi Oka, Masahito Nakazaki, Rie Onodera, Junpei Suzuki, Yuichi Sasaki, Hiroshi Nagahama, Jeffery D. Kocsis and Osamu Honmou
Intravenous infusion of mesenchymal stem cells (MSCs) derived from adult bone marrow improves behavioral function in rat models of cerebral infarction. Although clinical studies are ongoing, most studies have focused on the acute or subacute phase of stroke. In the present study, MSCs derived from bone marrow of rats were intravenously infused 8 weeks after the induction of a middle cerebral artery occlusion (MCAO) to investigate whether delayed systemic injection of MSCs improves functional outcome in the chronic phase of stroke in rats.
Eight weeks after induction of the MCAO, the rats were randomized and intravenously infused with either MSCs or vehicle. Ischemic volume and behavioral performance were examined. Blood-brain barrier (BBB) integrity was assessed by quantifying the leakage of Evans blue into the brain parenchyma after intravenous infusion. Immunohistochemical analysis was also performed to evaluate the stability of the BBB.
Motor recovery was better in the MSC-treated group than in the vehicle-treated group, with rapid improvement (evident at 1 week post-infusion). In MSC-treated rats, reduced BBB leakage and increased microvasculature/repair and neovascularization were observed.
These results indicate that the systemic infusion of MSCs results in functional improvement, which is associated with structural changes in the chronic phase of cerebral infarction, including in the stabilization of the BBB.
Masahito Nakazaki, Masanori Sasaki, Yuko Kataoka-Sasaki, Shinichi Oka, Takahiro Namioka, Ai Namioka, Rie Onodera, Junpei Suzuki, Yuichi Sasaki, Hiroshi Nagahama, Takeshi Mikami, Masahiko Wanibuchi, Jeffery D. Kocsis and Osamu Honmou
Reperfusion therapy with intravenous recombinant tissue plasminogen activator (rtPA) is the standard of care for acute ischemic stroke. However, hemorrhagic complications can result. Intravenous infusion of mesenchymal stem cells (MSCs) reduces stroke volume and improves behavioral function in experimental stroke models. One suggested therapeutic mechanism is inhibition of vascular endothelial dysfunction. The objective of this study was to determine whether MSCs suppress hemorrhagic events after rtPA therapy in the acute phase of transient middle cerebral artery occlusion (tMCAO) in rats.
After induction of tMCAO, 4 groups were studied: 1) normal saline [NS]+vehicle, 2) rtPA+vehicle, 3) NS+MSCs, and 4) rtPA+MSCs. The incidence rate of intracerebral hemorrhage, both hemorrhagic and ischemic volume, and behavioral performance were examined. Matrix metalloproteinase–9 (MMP-9) levels in the brain were assessed with zymography. Quantitative analysis of regional cerebral blood flow (rCBF) was performed to assess hemodynamic change in the ischemic lesion.
The MSC-treated groups (Groups 3 and 4) experienced a greater reduction in the incidence rate of intracerebral hemorrhage and hemorrhagic volume 1 day after tMCAO even if rtPA was received. The application of rtPA enhanced activation of MMP-9, but MSCs inhibited MMP-9 activation. Behavioral testing indicated that both MSC-infused groups had greater improvement than non-MSC groups had, but rtPA+MSCs provided greater improvement than MSCs alone. The rCBF ratio of rtPA groups (Groups 2 and 4) was similar at 2 hours after reperfusion of tMCAO, but both were greater than that in non-rtPA groups.
Infused MSCs may inhibit endothelial dysfunction to suppress hemorrhagic events and facilitate functional outcome. Combined therapy of infused MSCs after rtPA therapy facilitated early behavioral recovery.