Anti-inflammatory and hMSC combination therapy for traumatic brain injury

The long-term goal of our research program is to develop safe and effective therapies for traumatic brain injury (TBI), which is a major health issue with our military personnel in combat. The prevalence of TBI from all causes is estimated at ~2.5 to 3.7 million cases in the USA alone. Currently, there are no FDA-

approved drugs available to treat TBI. While TBI illness ranges from mild to severe, moderate TBI is clinically most relevant, and If not treated immediately the secondary injury in these patients could spread quickly and may lead to long-term consequences including cognitive and memory loss. Mesenchymal

stem cells (MSCs) transplantation has emerged as one of the major approaches to treat TBI. However, the viability of sole MSC therapy is being debated due to the uncertainty of variable engraftment in inflammatory state. Hence, there is a genuine unmet need to discover and develop new therapeutic agents for all forms of TBI, especially moderate TBI.

It has been reported that adding an anti-inflammatory agent prior to MSC treatment increased the latter’s efficacy. During the last funding period, we have established an experimental mouse model to enable characterization of the consequences of repeated TBI (rTBI) in closed head injury, which shows

extensive neuropathologic changes associated with the cognitive deficit, consistent with human TBI. We made the striking discovery that the expression of chemokine (C-C motif) ligand 20 (CCL20) (MIP3α) is pivotal to inflammation in TBI, implicating CCL20 as a potential TBI drug target. We have demonstrated that CCL20 inhibitor, pioglitazone (PG), played a key role in reducing astrogliosis,

microglial activation and inflammasome activation in TBI. A combination of PG and hMSC treatment not only reduced inflammation but also improved behavioral outcomes by increasing the expression of brain-derived neurotrophic factor (BDNF). Because PG is not a specific CCL20 inhibitor and may have off-target effects, we have established and validated a nanoformulation of short hairpin RNA

(shRNA) plasmids encoding CCL20 and its receptor CCR6 using dendrimer. A combination treatment involving shCCL20/shCCR6 (shCombo) and human MSC (hMSC) showed a significant reduction in inflammation, a concomitant increase in BDNF and neurogenesis in rTBI mouse model. Based on our preliminary data, we hypothesize that the shCombo dendriplex (DPX) or/and

hMSC combination regimen will attenuate both acute brain- and systemic-inflammation by decreasing activation of glial cells and astrocytes in the brain, and secreting trophic factors over a prolonged period, which in turn promotes neuronal remodeling in the damaged brain and provides sustained relief from TBI-induced pathology. Three specific aims are proposed to test this hypothesis. In

Aim #1, we will determine the optimal dose of pshCombo-DPX and the therapeutic window of treatment in rTBI mice. In Aim #2 we will examine the short-term and long-term effects of shCombo-DPX or/and hMSC therapy on pathophysiology and behavioral deficits in rTBI mice. In Aim #3, we will determine the mechanism of action of CCL20 in rTBI-induced pathogenesis and behavioral deficits.

This highly innovative proposal aims to investigate whether shCombo-DPX as a single agent or in combination with hMSC will reduce acute brain- and systemic-inflammation and behavioral deficits, and plans to address the mechanism of action and surrogate markers of efficacy based on genes induced during acute inflammation. The proposed translational research based on a rationally designed better

anti-inflammatory therapy is expected to increase our understanding of the long-term outcome of the therapy for mild to moderate TBI and pave the way for future clinical translation.