Restoration of lost neuronal function after spinal cord injury (SCI) still remains a big challeng... more Restoration of lost neuronal function after spinal cord injury (SCI) still remains a big challenge for current medicine. One important repair strategy is bridging the SCI lesion with a supportive and stimulatory milieu that would enable axonal rewiring. Injectable extracellular matrix (ECM) derived hydrogels have been recently reported to have neurotrophic potential in vitro. In this study, we evaluated the presumed neuroregenerative properties of ECM hydrogels in vivo in the acute model of SCI. ECM hydrogels were prepared by decellularization of porcine spinal cord (SC) or porcine urinary bladder (UB), and injected into a spinal cord hemisection cavity. Histological analysis and real-time qPCR were performed at 2, 4 and 8 weeks post-injection. Both types of hydrogels integrated into the lesion and stimulated neovascularization and axonal ingrowth into the lesion. On the other hand, massive infiltration of macrophages into the lesion and rapid hydrogel degradation did not prevent cy...
Small (Weinheim an der Bergstrasse, Germany), Jan 30, 2015
Manganese oxide nanoparticles (MONPs) are capable of time-dependent magnetic resonance imaging co... more Manganese oxide nanoparticles (MONPs) are capable of time-dependent magnetic resonance imaging contrast switching as well as releasing a surface-bound drug. MONPs give T2/T2* contrast, but dissolve and release T1-active Mn(2+) and L-3,4-dihydroxyphenylalanine. Complementary images are acquired with a single contrast agent, and applications toward Parkinson's disease are suggested.
Expert opinion on biological therapy, Jan 30, 2015
Stroke is one of the most devastating diseases and a leading cause of mortality worldwide. So far... more Stroke is one of the most devastating diseases and a leading cause of mortality worldwide. So far, clinical management of stroke involves surgical clot retrieval or thrombolytic treatment inducing reperfusion of the occluded vessels in the cerebral infarcted area, which is dependent on early intervention following insult. New treatment strategies involve the promotion of angiogenesis and neuroplasticity, stimulation of endogenous neurogenesis, remyelinization, and immunomodulation by means of cell transplantation and sustained drug delivery. Areas covered: This review describes different types of stem cells (endogenous and exogenous neural progenitors, pluripotent stem cell derivatives, mesenchymal stem cells [MSCs], olfactory ensheathing cells) and biomaterials, their routes of administration, means of noninvasive imaging, and the prerequisites and hurdles for the successful translation of the cell therapies to the clinic. Expert opinion: Neural precursors (NPs) derived from plurip...
Stroke is one of the most devastating diseases and a leading cause of mortality worldwide. So far... more Stroke is one of the most devastating diseases and a leading cause of mortality worldwide. So far, clinical management of stroke involves surgical clot retrieval or thrombolytic treatment inducing reperfusion of the occluded vessels in the cerebral infarcted area, which is dependent on early intervention following insult. New treatment strategies involve the promotion of angiogenesis and neuroplasticity, stimulation of endogenous neurogenesis, remyelinization, and immunomodulation by means of cell transplantation and sustained drug delivery. Areas covered: This review describes different types of stem cells (endogenous and exogenous neural progenitors, pluripotent stem cell derivatives, mesenchymal stem cells [MSCs], olfactory ensheathing cells) and biomaterials, their routes of administration, means of noninvasive imaging, and the prerequisites and hurdles for the successful translation of the cell therapies to the clinic. Expert opinion: Neural precursors (NPs) derived from pluripotent stem cells, unlike MSCs, can not only remodel the CNS by promoting neuroplasticity, angiogenesis, and immunomodulation, but also replace damaged cells. To transfer NPs into the clinic, step by step guidelines for researchers are identified and discussed.
Transferrin (Tf) conjugated to gold nanoparticles and clusters combine the protein&am... more Transferrin (Tf) conjugated to gold nanoparticles and clusters combine the protein's site-specific receptor targeting capabilities with the optical properties imparted by the nano-sized gold. We have described two different synthesis protocols, one yielding fluorescent Tf-stabilized gold nanoclusters (AuNCs) and one yielding Tf-stabilized gold nanoparticles that exhibit localized surface plasmon resonance. We demonstrate that the synthetic route employed has a large influence both on the gold nanostructure formed, and also on the structural integrity of the protein. A slight protein unfolding allows stronger interaction with lipids, and was found to significantly perturb lipid monolayers. Interactions between the protein-gold nanostructures and three different cell types were also assessed, indicating that the enhanced membrane affinity may be attributed to intercellular membrane differences.
The purpose of the present study was to use magnetic resonance imaging (MRI) as a tool for monito... more The purpose of the present study was to use magnetic resonance imaging (MRI) as a tool for monitoring transplant-mediated repair of the adult rat visual pathway. We labelled rat olfactory ensheathing cells (OECs) using micron-sized particles of iron oxide (MPIO) and transplanted them by: i) intravitreal injection (ivit) and ii) intra-optic nerve (ON) injection (iON) in adult rats with ON crush (ONC) injury. We applied T(2)-weighted MRI and manganese-enhanced MRI (MEMRI) to visualise transplanted cells and ON axons at specific times after injury and cell engraftment. Our findings demonstrate that ivit MPIO-labelled OECs are unequivocally detected by T(2)-weighted MRI in vivo and that the T(1)-weighted 3D FLASH sequence applied for MEMRI facilitates simultaneous visualisation of Mn(2+-) enhanced regenerating retinal ganglion cell (RGC) axons and MPIO-labelled OEC grafts. Furthermore, analysis of MRI data and ultrastructural findings supports the hypothesis that iON OEC transplants mediate regeneration and remyelination of RGC axons post injury.
To evaluate manganese (Mn(2+))-enhanced MRI (MEMRI) and diffusion tensor imaging (DTI) as tools f... more To evaluate manganese (Mn(2+))-enhanced MRI (MEMRI) and diffusion tensor imaging (DTI) as tools for detection of axonal injury and regeneration after intravitreal peripheral nerve graft (PNG) implantation in the rat optic nerve (ON). In adult Fischer rats, retinal ganglion cell (RGC) survival was evaluated in Flurogold (FG) back-filled retinal whole mounts after ON crush (ONC), intravitreal PNG, and intravitreal MnCl(2) injection (150 nmol) at 0 and 20 days post lesion (dpl). MEMRI and echo-planar DTI (DTI-EPI) was obtained of noninjured ON one day after intravitreal MnCl(2) injection, and at 1 and 21 dpl after ONC, intravitreal PNG, and intravitreal MnCl(2) injections given at 0 and 20 dpl. GAP-43 immunohistochemistry was performed after the last MRI. ONC reduced RGC density in retina by 94% at 21 dpl compared to noninjured ON without MnCl(2) injections. Both intravitreal PNG and intravitreal MnCl(2) injections improved RGC survival in retina, which was reduced by 90% (ONC+MnCl(2)), 82% (ONC+PNG), and 74% (ONC+PNG+MnCl(2)) compared to noninjured ON. DTI-derived parameters (fractional anisotropy [FA], mean diffusivity, axial diffusivity lambda( parallel), and radial diffusivity lambda( perpendicular)) were unaffected by the presence of Mn(2+) in the ON. At 1 dpl, CNR(MEMRI) and lambda( parallel) were reduced at the injury site, while at 21 dpl they were increased at the injury site compared to values measured at 1 dpl. GAP-43 immunoreactive axons were present in the ON distal to the ONC injury site. MEMRI and DTI enabled detection of functional and structural degradation after rat ON injury, and there was correlation between the MRI-derived and immunohistochemical measures of axon regeneration.
To evaluate manganese (Mn2+)-enhanced MRI in a longitudinal study of normal and injured rat visua... more To evaluate manganese (Mn2+)-enhanced MRI in a longitudinal study of normal and injured rat visual projections. MRI was performed 24 hours after unilateral intravitreal injection of MnCl2 (150 nmol) into adult Fischer rats that were divided into four groups: 1) controls (N = 5), 2) dose-response (N = 10, 0.2-200 nmol), 3) time-response with repeated MRI during 24-168 hours post injection (N = 4), and 4) optic nerve crush (ONC) immediately preceding the MnCl2 injection (N = 7). Control and ONC animals were reinjected with MnCl2 20 days after the first injection, and MRI was performed 24 hours later. In the control group, the optic projection was visualized from the retina to the superior colliculus, with indications of transsynaptic transport to the cortex. There was a semilogarithmic relationship between the Mn2+ dose and Mn2+ enhancement from 4 to 200 nmol, and the enhancement decayed gradually to 0 by 168 hours. No Mn2+-enhanced signal was detected distal to the ON crush site. In the control group, similar enhancement was obtained after the first and second MnCl2 injections, while in the ONC group the enhancement proximal to the crush site was reduced 20 days post lesion (20 dpl). Mn2+-enhanced MRI is a viable method for temporospatial visualization of normal and injured ON in the adult rat. The observed reduction in the Mn2+ signal proximal to the ONC is probably a result of retrograde damage to the retinal ganglion cells, and not of Mn2+ toxicity.
Journal of controlled release : official journal of the Controlled Release Society, Jan 27, 2015
The blood-brain barrier (BBB) constitutes a significant obstacle for the delivery of drugs into t... more The blood-brain barrier (BBB) constitutes a significant obstacle for the delivery of drugs into the central nervous system (CNS). Nanoparticles have been able to partly overcome this obstacle and can thus improve drug delivery across the BBB. Furthermore, focused ultrasound in combination with gas filled microbubbles has opened the BBB in a temporospatial manner in animal models, thus facilitating drug delivery across the BBB. In the current study we combine these two approaches in our quest to develop a novel, generic method for drug delivery across the BBB and into the CNS. Nanoparticles were synthesized using the polymer poly(butyl cyanoacrylate) (PBCA), and such nanoparticles have been reported to cross the BBB to some extent. Together with proteins, these nanoparticles self-assemble into microbubbles. Using these novel microbubbles in combination with focused ultrasound, we successfully and safely opened the BBB transiently in healthy rats. Furthermore, we also demonstrated tha...
Restoration of lost neuronal function after spinal cord injury (SCI) still remains a big challeng... more Restoration of lost neuronal function after spinal cord injury (SCI) still remains a big challenge for current medicine. One important repair strategy is bridging the SCI lesion with a supportive and stimulatory milieu that would enable axonal rewiring. Injectable extracellular matrix (ECM) derived hydrogels have been recently reported to have neurotrophic potential in vitro. In this study, we evaluated the presumed neuroregenerative properties of ECM hydrogels in vivo in the acute model of SCI. ECM hydrogels were prepared by decellularization of porcine spinal cord (SC) or porcine urinary bladder (UB), and injected into a spinal cord hemisection cavity. Histological analysis and real-time qPCR were performed at 2, 4 and 8 weeks post-injection. Both types of hydrogels integrated into the lesion and stimulated neovascularization and axonal ingrowth into the lesion. On the other hand, massive infiltration of macrophages into the lesion and rapid hydrogel degradation did not prevent cy...
Small (Weinheim an der Bergstrasse, Germany), Jan 30, 2015
Manganese oxide nanoparticles (MONPs) are capable of time-dependent magnetic resonance imaging co... more Manganese oxide nanoparticles (MONPs) are capable of time-dependent magnetic resonance imaging contrast switching as well as releasing a surface-bound drug. MONPs give T2/T2* contrast, but dissolve and release T1-active Mn(2+) and L-3,4-dihydroxyphenylalanine. Complementary images are acquired with a single contrast agent, and applications toward Parkinson's disease are suggested.
Expert opinion on biological therapy, Jan 30, 2015
Stroke is one of the most devastating diseases and a leading cause of mortality worldwide. So far... more Stroke is one of the most devastating diseases and a leading cause of mortality worldwide. So far, clinical management of stroke involves surgical clot retrieval or thrombolytic treatment inducing reperfusion of the occluded vessels in the cerebral infarcted area, which is dependent on early intervention following insult. New treatment strategies involve the promotion of angiogenesis and neuroplasticity, stimulation of endogenous neurogenesis, remyelinization, and immunomodulation by means of cell transplantation and sustained drug delivery. Areas covered: This review describes different types of stem cells (endogenous and exogenous neural progenitors, pluripotent stem cell derivatives, mesenchymal stem cells [MSCs], olfactory ensheathing cells) and biomaterials, their routes of administration, means of noninvasive imaging, and the prerequisites and hurdles for the successful translation of the cell therapies to the clinic. Expert opinion: Neural precursors (NPs) derived from plurip...
Stroke is one of the most devastating diseases and a leading cause of mortality worldwide. So far... more Stroke is one of the most devastating diseases and a leading cause of mortality worldwide. So far, clinical management of stroke involves surgical clot retrieval or thrombolytic treatment inducing reperfusion of the occluded vessels in the cerebral infarcted area, which is dependent on early intervention following insult. New treatment strategies involve the promotion of angiogenesis and neuroplasticity, stimulation of endogenous neurogenesis, remyelinization, and immunomodulation by means of cell transplantation and sustained drug delivery. Areas covered: This review describes different types of stem cells (endogenous and exogenous neural progenitors, pluripotent stem cell derivatives, mesenchymal stem cells [MSCs], olfactory ensheathing cells) and biomaterials, their routes of administration, means of noninvasive imaging, and the prerequisites and hurdles for the successful translation of the cell therapies to the clinic. Expert opinion: Neural precursors (NPs) derived from pluripotent stem cells, unlike MSCs, can not only remodel the CNS by promoting neuroplasticity, angiogenesis, and immunomodulation, but also replace damaged cells. To transfer NPs into the clinic, step by step guidelines for researchers are identified and discussed.
Transferrin (Tf) conjugated to gold nanoparticles and clusters combine the protein&am... more Transferrin (Tf) conjugated to gold nanoparticles and clusters combine the protein's site-specific receptor targeting capabilities with the optical properties imparted by the nano-sized gold. We have described two different synthesis protocols, one yielding fluorescent Tf-stabilized gold nanoclusters (AuNCs) and one yielding Tf-stabilized gold nanoparticles that exhibit localized surface plasmon resonance. We demonstrate that the synthetic route employed has a large influence both on the gold nanostructure formed, and also on the structural integrity of the protein. A slight protein unfolding allows stronger interaction with lipids, and was found to significantly perturb lipid monolayers. Interactions between the protein-gold nanostructures and three different cell types were also assessed, indicating that the enhanced membrane affinity may be attributed to intercellular membrane differences.
The purpose of the present study was to use magnetic resonance imaging (MRI) as a tool for monito... more The purpose of the present study was to use magnetic resonance imaging (MRI) as a tool for monitoring transplant-mediated repair of the adult rat visual pathway. We labelled rat olfactory ensheathing cells (OECs) using micron-sized particles of iron oxide (MPIO) and transplanted them by: i) intravitreal injection (ivit) and ii) intra-optic nerve (ON) injection (iON) in adult rats with ON crush (ONC) injury. We applied T(2)-weighted MRI and manganese-enhanced MRI (MEMRI) to visualise transplanted cells and ON axons at specific times after injury and cell engraftment. Our findings demonstrate that ivit MPIO-labelled OECs are unequivocally detected by T(2)-weighted MRI in vivo and that the T(1)-weighted 3D FLASH sequence applied for MEMRI facilitates simultaneous visualisation of Mn(2+-) enhanced regenerating retinal ganglion cell (RGC) axons and MPIO-labelled OEC grafts. Furthermore, analysis of MRI data and ultrastructural findings supports the hypothesis that iON OEC transplants mediate regeneration and remyelination of RGC axons post injury.
To evaluate manganese (Mn(2+))-enhanced MRI (MEMRI) and diffusion tensor imaging (DTI) as tools f... more To evaluate manganese (Mn(2+))-enhanced MRI (MEMRI) and diffusion tensor imaging (DTI) as tools for detection of axonal injury and regeneration after intravitreal peripheral nerve graft (PNG) implantation in the rat optic nerve (ON). In adult Fischer rats, retinal ganglion cell (RGC) survival was evaluated in Flurogold (FG) back-filled retinal whole mounts after ON crush (ONC), intravitreal PNG, and intravitreal MnCl(2) injection (150 nmol) at 0 and 20 days post lesion (dpl). MEMRI and echo-planar DTI (DTI-EPI) was obtained of noninjured ON one day after intravitreal MnCl(2) injection, and at 1 and 21 dpl after ONC, intravitreal PNG, and intravitreal MnCl(2) injections given at 0 and 20 dpl. GAP-43 immunohistochemistry was performed after the last MRI. ONC reduced RGC density in retina by 94% at 21 dpl compared to noninjured ON without MnCl(2) injections. Both intravitreal PNG and intravitreal MnCl(2) injections improved RGC survival in retina, which was reduced by 90% (ONC+MnCl(2)), 82% (ONC+PNG), and 74% (ONC+PNG+MnCl(2)) compared to noninjured ON. DTI-derived parameters (fractional anisotropy [FA], mean diffusivity, axial diffusivity lambda( parallel), and radial diffusivity lambda( perpendicular)) were unaffected by the presence of Mn(2+) in the ON. At 1 dpl, CNR(MEMRI) and lambda( parallel) were reduced at the injury site, while at 21 dpl they were increased at the injury site compared to values measured at 1 dpl. GAP-43 immunoreactive axons were present in the ON distal to the ONC injury site. MEMRI and DTI enabled detection of functional and structural degradation after rat ON injury, and there was correlation between the MRI-derived and immunohistochemical measures of axon regeneration.
To evaluate manganese (Mn2+)-enhanced MRI in a longitudinal study of normal and injured rat visua... more To evaluate manganese (Mn2+)-enhanced MRI in a longitudinal study of normal and injured rat visual projections. MRI was performed 24 hours after unilateral intravitreal injection of MnCl2 (150 nmol) into adult Fischer rats that were divided into four groups: 1) controls (N = 5), 2) dose-response (N = 10, 0.2-200 nmol), 3) time-response with repeated MRI during 24-168 hours post injection (N = 4), and 4) optic nerve crush (ONC) immediately preceding the MnCl2 injection (N = 7). Control and ONC animals were reinjected with MnCl2 20 days after the first injection, and MRI was performed 24 hours later. In the control group, the optic projection was visualized from the retina to the superior colliculus, with indications of transsynaptic transport to the cortex. There was a semilogarithmic relationship between the Mn2+ dose and Mn2+ enhancement from 4 to 200 nmol, and the enhancement decayed gradually to 0 by 168 hours. No Mn2+-enhanced signal was detected distal to the ON crush site. In the control group, similar enhancement was obtained after the first and second MnCl2 injections, while in the ONC group the enhancement proximal to the crush site was reduced 20 days post lesion (20 dpl). Mn2+-enhanced MRI is a viable method for temporospatial visualization of normal and injured ON in the adult rat. The observed reduction in the Mn2+ signal proximal to the ONC is probably a result of retrograde damage to the retinal ganglion cells, and not of Mn2+ toxicity.
Journal of controlled release : official journal of the Controlled Release Society, Jan 27, 2015
The blood-brain barrier (BBB) constitutes a significant obstacle for the delivery of drugs into t... more The blood-brain barrier (BBB) constitutes a significant obstacle for the delivery of drugs into the central nervous system (CNS). Nanoparticles have been able to partly overcome this obstacle and can thus improve drug delivery across the BBB. Furthermore, focused ultrasound in combination with gas filled microbubbles has opened the BBB in a temporospatial manner in animal models, thus facilitating drug delivery across the BBB. In the current study we combine these two approaches in our quest to develop a novel, generic method for drug delivery across the BBB and into the CNS. Nanoparticles were synthesized using the polymer poly(butyl cyanoacrylate) (PBCA), and such nanoparticles have been reported to cross the BBB to some extent. Together with proteins, these nanoparticles self-assemble into microbubbles. Using these novel microbubbles in combination with focused ultrasound, we successfully and safely opened the BBB transiently in healthy rats. Furthermore, we also demonstrated tha...
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Papers by Axel Sandvig