Forced forelimb use following stroke enhances oligodendrogenesis and functional recovery in the rat

The NG2-glia is a potential target to maintain the integrity of neurovascular unit after acute ischemic stroke

The neurovascular unit (NVU) plays a critical role in health and disease. In the current review, we discuss the critical role of a class of neural/glial antigen 2 (NG2)-expressing glial cells (NG2-glia) in regulating NVU after acute ischemic stroke (AIS). We first introduce the role of NG2-glia in the formation of NVU during development as well as aging-induced damage to NVU and accompanying NG2-glia change. We then discuss the reciprocal interactions between NG2-glia and the other component cells of NVU, emphasizing the factors that could influence NG2-glia. Damage to the NVU integrity is the pathological basis of edema and hemorrhagic transformation, the most dreaded complication after AIS. The role of NG2-glia in AIS-induced NVU damage and the effect of NG2-glia transplantation on AIS-induced NVU damage are summarized. We next discuss the role of NG2-glia and the effect of NG2-glia transplantation in oligodendrogenesis and white matter repair as well as angiogenesis which is associated with the outcome of the patients after AIS. Finally, we review the current strategies to promote NG2-glia proliferation and differentiation and propose to use the dental pulp stem cells (DPSC)-derived exosome as a promising strategy to reduce AIS-induced injury and promote repair through maintaining the integrity of NVU by regulating endogenous NG2-glia proliferation and differentiation.

Reorganization of Ventral Premotor Cortex After Ischemic Brain Injury: Effects of Forced Use

BACKGROUND

Physical use of the affected upper extremity can have a beneficial effect on motor recovery in people after stroke. Few studies have examined neurological mechanisms underlying the effects of forced use in non-human primates. In particular, the ventral premotor cortex (PMV) has been previously implicated in recovery after injury.

OBJECTIVE

To examine changes in motor maps in PMV after a period of forced use following ischemic infarct in primary motor cortex (M1).

METHODS

Intracortical microstimulation (ICMS) techniques were used to derive motor maps in PMV of four adult squirrel monkeys before and after an experimentally induced ischemic infarct in the M1 distal forelimb area (DFL) in the dominant hemisphere. Monkeys wore a sleeved jacket (generally 24 hrs/day) that forced limb use contralateral to the infarct in tasks requiring skilled digit use. No specific rehabilitative training was provided.

RESULTS

At 3 mos post-infarct, ICMS maps revealed a significant expansion of the DFL representation in PMV relative to pre-infarct baseline (mean = +77.3%; n = 3). Regression analysis revealed that the magnitude of PMV changes was largely driven by M1 lesion size, with a modest effect of forced use. One additional monkey examined after ∼18 months of forced use demonstrated a 201.7% increase, unprecedented in non-human primate studies.

CONCLUSIONS

Functional reorganization in PMV following an ischemic infarct in the M1 DFL is primarily driven by M1 lesion size. Additional expansion occurs in PMV with extremely long periods of forced use but such extended constraint is not considered clinically feasible.