To label mammalian and stem cells by combining commercially available transfection agents (TAs) with superparamagnetic iron oxide (SPIO) magnetic resonance (MR) imaging contrast agents. Three TAs were incubated with ferumoxides and MION-46L in cell culture medium at various concentrations. Human mesenchymal stem cells, mouse lymphocytes, rat oligodendrocyte progenitor CG-4 cells, and human cervical carcinoma cells were incubated 2-48 hours with 25 microg of iron per milliliter of combined TAs and SPIO. Cellular labeling was evaluated with T2 relaxometry, MR imaging of labeled cell suspensions, and Prussian blue staining for iron assessment. Proliferation and viability of mesenchymal stem cells and human cervical carcinoma cells labeled with a combination of TAs and ferumoxides were evaluated. When ferumoxides-TA or MION-46L-TA was used, intracytoplasmic particles stained with Prussian blue stain were detected for all cell lines with a labeling efficiency of nearly 100%. Limited or no uptake was observed for cells incubated with ferumoxides or MION-46L alone. For TA-SPIO-labeled cells, MR images and relaxometry findings showed a 50%-90% decrease in signal intensity and a more than 40-fold increase in T2s. Cell viability varied from 103.7% +/- 9 to 123.0% +/- 9 compared with control cell viability at 9 days, and cell proliferation was not affected by endosomal incorporation of SPIO nanoparticles. Iron concentrations varied with ferumoxides-TA combinations and cells with a maximum of 30.1 pg +/- 3.7 of iron per cell for labeled mesenchymal stem cells. Magnetic labeling of mammalian cells with use of ferumoxides and TAs is possible and may enable cellular MR imaging and tracking in experimental and clinical settings.

After central nervous system injury, inflammatory macrophages (M1) predominate over anti-inflammatory macrophages (M2). The temporal profile of M1/M2 phenotypes in macrophages and microglia after traumatic brain injury (TBI) in rats is unknown. We subjected female rats to severe controlled cortical impact (CCI) and examined the postinjury M1/M2 time course in their brains.

There are currently no good ways to track human cells in vivo in a clinical setting using magnetic resonance imaging (MRI) based on superparamagnetic iron-oxide nanoparticles. Mya Thu and colleagues have introduced a simple magnetic cell labeling approach that combines three currently US Food and Drug Administration–approved drugs—ferumoxytol, heparin and protamine—to form self-assembling nanocomplexes of about 150 nm in size that effectively label cells for MRI. The approach was shown to effectively label three types of stem cells and two types of immune cells. We report on a new straightforward magnetic cell-labeling approach that combines three US Food and Drug Administration (FDA)-approved drugs—ferumoxytol, heparin and protamine—in serum-free medium to form self-assembling nanocomplexes that effectively label cells for in vivo magnetic resonance imaging (MRI). We observed that the ferumoxytol-heparin-protamine (HPF) nanocomplexes were stable in serum-free cell culture medium. HPF nanocomplexes show a threefold increase in T2 relaxivity compared to ferumoxytol. Electron microscopy showed internalized HPF in endosomes, which we confirmed by Prussian blue staining of labeled cells. There was no long-term effect or toxicity on cellular physiology or function of HPF-labeled hematopoietic stem cells, bone marrow stromal cells, neural stem cells or T cells when compared to controls. In vivo MRI detected 1,000 HPF-labeled cells implanted in rat brains. This HPF labeling method should facilitate the monitoring by MRI of infused or implanted cells in clinical trials.

Significance: Disruption of the blood–brain barrier (BBB) for drug delivery to the central nervous system (CNS) is achieved clinically through intracarotid artery hyperosmotic mannitol (ICAHM) infusions. However, ICAHM is often viewed as a simple drug delivery mechanism, and biological implications have been largely overlooked. This study demonstrates that BBB disruption by ICAHM generates a transient sterile neuroinflammatory response marked by increased production of cytokines, chemokines, and trophic factors leading activation of astrocytes, microglia, and macrophages. Additionally, unilateral ICAHM generates plasma increases in inflammatory molecules with evidence of sterile inflammation on the untreated contralateral hemisphere. These biological responses to ICAHM suggest its potential for immune modulation in several CNS pathologies.

Objective: To determine the effect of interferon-β-1b (IFNβ-1b) treatment on total contrast-enhancing lesions (CEL), white matter lesion load (WMLL), and cerebral atrophy (CA) in patients with relapsing–remitting multiple sclerosis (RRMS) using serial monthly MRI. Methods: An open-label baseline-vs-treatment crossover trial was conducted with 30 RRMS patients monitored during a 6-month baseline and up to 36 months on treatment with IFNβ-1b. Monthly MRI exams and neurologic exams using the Expanded Disability Status Scale (EDSS) were performed. Results: The percentage changes from baseline for years 1, 2, and 3 on IFNβ-1b were as follows: brain volume (BV) = −1.35, −1.48, and −1.68%; CEL = −76.5, −60.1, and −54.7%; WMLL = −12.2, −9.8, and −10.4%. There was no difference in the BV, CEL, or WMLL for between-year comparisons, and the decrease in BV from year 1 to years 2 and 3 was less than the change from baseline to year 1. EDSS did increase (p < 0.001) when comparing the last 3 months of baseline (2.8 ± 2.1) and the last 3 months on IFNβ-1b (3.6 ± 2.1). Eleven patients developed neutralizing antibody (NAb) during the study. The effect of IFNβ-1b on CEL and WMLL was significantly reduced in NAb+ patients compared with NAb− patients (p < 0.003). Conclusion: IFNβ-1b decreases contrast-enhancing lesions and white matter lesion load over 3 years on therapy and slows the progression in cerebral atrophy during years 2 and 3.

Continuous focused ultrasound (cFUS) has been widely used for thermal ablation of tissues, relying on continuous exposures to generate temperatures necessary to induce coagulative necrosis. Pulsed FUS (pFUS) employs non-continuous exposures that lower the rate of energy deposition and allow cooling to occur between pulses, thereby minimizing thermal effects and emphasizing effects created by non-thermal mechanisms of FUS (i.e., acoustic radiation forces and acoustic cavitation). pFUS has shown promise for a variety of applications including drug and nanoparticle delivery; however, little is understood about the effects these exposures have on tissue, especially with regard to cellular pro-homing factors (growth factors, cytokines, and cell adhesion molecules). We examined changes in murine hamstring muscle following pFUS or cFUS and demonstrate that pFUS, unlike cFUS, has little effect on the histological integrity of muscle and does not induce cell death. Infiltration of macrophages was observed 3 and 8 days following pFUS or cFUS exposures. pFUS increased expression of several cytokines (e.g., IL-1α, IL-1β, TNFα, INFγ, MIP-1α, MCP-1, and GMCSF) creating a local cytokine gradient on days 0 and 1 post-pFUS that returns to baseline levels by day 3 post-pFUS. pFUS exposures induced upregulation of other signaling molecules (e.g., VEGF, FGF, PlGF, HGF, and SDF-1α) and cell adhesion molecules (e.g., ICAM-1 and VCAM-1) on muscle vasculature. The observed molecular changes in muscle following pFUS may be utilized to target cellular therapies by increasing homing to areas of pathology.