Multiparametric, Longitudinal Optical Coherence Tomography Imaging Reveals Acute Injury and Chronic Recovery in Experimental Ischemic Stroke

Progress in experimental stroke and translational medicine could be accelerated by high-resolution in vivo imaging of disease progression in the mouse cortex. Here, we introduce optical microscopic methods that monitor brain injury progression using intrinsic optical scattering properties of cortical tissue. A multi-parametric Optical Coherence Tomography (OCT) platform for longitudinal imaging of ischemic stroke in mice, through thinned-skull, reinforced cranial window surgical preparations, is described. In the acute stages, the spatiotemporal interplay between hemodynamics and cell viability, a key determinant of pathogenesis, was imaged. In acute stroke, microscopic biomarkers for eventual infarction, including capillary non-perfusion, cerebral blood flow deficiency, altered cellular scattering, and impaired autoregulation of cerebral blood flow, were quantified and correlated with histology. Additionally, longitudinal microscopy revealed remodeling and flow recovery after one week of chronic stroke. Intrinsic scattering properties serve as reporters of acute cellular and vascular injury and recovery in experimental stroke. Multi-parametric OCT represents a robust in vivo imaging platform to comprehensively investigate these properties

Facial-nerve regeneration ability of a hybrid artificial nerve conduit containing uncultured adipose-derived stromal vascular fraction: An experimental study

This study investigated the potential of uncultured-stromal-vascular-fraction (SVF) cells in promoting facial nerve regeneration in a rat model

Adipose-derived aldehyde dehydrogenase-expressing cells promote dermal regenerative potential with collagen-glycosaminoglycan scaffold

Aldehyde dehydrogenase (ALDH) is an enzyme that plays an important role in retinoid metabolism and highly expressed in stem cells. This study isolated ALDH-expressing cells from subcutaneous adipose tissue and investigated their potential to enhance healing in a full-thickness skin wound in rats by co-implanting them with collagen-glycosaminoglycan (c-GAG) scaffolds. ALDH-positive cells were isolated by a fluorescence-activated cell sorting technique from Lewis rat's stromal-vascular-fraction (SVF) and transplanted with c-GAG scaffolds in a rat full-thickness skin wound model. At 7 days after surgery, the microscopic appearance of c-GAG scaffolds seeded with ALDH-positive was compared with those of uncultured-SVF, and cultured-SVF adipose-derived stromal cells (ASCs). The thickness of cellular ingrowth in the ASC group (630\u2009\ub1\u2009180 \u3bcm) was significantly thicker than that in the control (390\u2009\ub1\u2009120 \u3bcm) or SVF (380\u2009\ub1\u2009140 \u3bcm) groups, but non-significantly thicker than that in the ALDH-positive group (570\u2009\ub1\u2009220 \u3bcm). The thickness of regenerated collagen layer was significantly thicker in the ALDH-positive group (160\u2009\ub1\u2009110 \u3bcm) than in the ASCs (81\u2009\ub1\u200941 \u3bcm), the control (65\u2009\ub1\u200924 \u3bcm), or SVF (64\u2009\ub1\u200934 \u3bcm) groups. Immunofluorescent staining with CD31 proved that transplanted ALDH-positive cells differentiated into vascular endothelial cells in c-GAG scaffolds. Combined transplantation with c-GAG scaffolds and adipose-derived ALDH-positive cells promoted dermal regeneration, giving a possibility that ALDH-positive cells would greatly shorten the waiting period before secondary autologous skin grafting was possible

Adipose-derived aldehyde dehydrogenase-expressing cells promote dermal regenerative potential with collagen-glycosaminoglycan scaffold

Aldehyde dehydrogenase (ALDH) is an enzyme that plays an important role in retinoid metabolism and highly expressed in stem cells. This study isolated ALDH-expressing cells from subcutaneous adipose tissue and investigated their potential to enhance healing in a full-thickness skin wound in rats by co-implanting them with collagen-glycosaminoglycan (c-GAG) scaffolds. ALDH-positive cells were isolated by a fluorescence-activated cell sorting technique from Lewis rat's stromal-vascular-fraction (SVF) and transplanted with c-GAG scaffolds in a rat full-thickness skin wound model. At 7 days after surgery, the microscopic appearance of c-GAG scaffolds seeded with ALDH-positive was compared with those of uncultured-SVF, and cultured-SVF adipose-derived stromal cells (ASCs). The thickness of cellular ingrowth in the ASC group (630 ± 180 μm) was significantly thicker than that in the control (390 ± 120 μm) or SVF (380 ± 140 μm) groups, but non-significantly thicker than that in the ALDH-positive group (570 ± 220 μm). The thickness of regenerated collagen layer was significantly thicker in the ALDH-positive group (160 ± 110 μm) than in the ASCs (81 ± 41 μm), the control (65 ± 24 μm), or SVF (64 ± 34 μm) groups. Immunofluorescent staining with CD31 proved that transplanted ALDH-positive cells differentiated into vascular endothelial cells in c-GAG scaffolds. Combined transplantation with c-GAG scaffolds and adipose-derived ALDH-positive cells promoted dermal regeneration, giving a possibility that ALDH-positive cells would greatly shorten the waiting period before secondary autologous skin grafting was possible

Multiparametric, longitudinal optical coherence tomography imaging reveals acute injury and chronic recovery in experimental ischemic stroke.

Progress in experimental stroke and translational medicine could be accelerated by high-resolution in vivo imaging of disease progression in the mouse cortex. Here, we introduce optical microscopic methods that monitor brain injury progression using intrinsic optical scattering properties of cortical tissue. A multi-parametric Optical Coherence Tomography (OCT) platform for longitudinal imaging of ischemic stroke in mice, through thinned-skull, reinforced cranial window surgical preparations, is described. In the acute stages, the spatiotemporal interplay between hemodynamics and cell viability, a key determinant of pathogenesis, was imaged. In acute stroke, microscopic biomarkers for eventual infarction, including capillary non-perfusion, cerebral blood flow deficiency, altered cellular scattering, and impaired autoregulation of cerebral blood flow, were quantified and correlated with histology. Additionally, longitudinal microscopy revealed remodeling and flow recovery after one week of chronic stroke. Intrinsic scattering properties serve as reporters of acute cellular and vascular injury and recovery in experimental stroke. Multi-parametric OCT represents a robust in vivo imaging platform to comprehensively investigate these properties

Bioengineered Self-assembled Skin as an Alternative to Skin Grafts

For patients with extensive burns or donor site scarring, the limited availability of autologous and the inevitable rejection of allogeneic skin drive the need for new alternatives. Existing engineered biologic and synthetic skin analogs serve as temporary coverage until sufficient autologous skin is available. Here we report successful engraftment of a self-assembled bilayered skin construct derived from autologous skin punch biopsies in a porcine model. Dermal fibroblasts were stimulated to produce an extracellular matrix and were then seeded with epidermal progenitor cells to generate an epidermis. Autologous constructs were grafted onto partial- and full-thickness wounds. By gross examination and histology, skin construct vascularization and healing were comparable to autologous skin grafts and were superior to an autologous bilayered living cellular construct fabricated with fibroblasts cast in bovine collagen. This is the first demonstration of spontaneous vascularization and permanent engraftment of a self-assembled bilayered bioengineered skin that could supplement existing methods of reconstruction

Spatially heterogeneous flow and diameter changes were observed during fMCAO and after reperfusion.

<p>Absolute flow maps show uniform flow at baseline (A), preferentially reduced MCA flow during occlusion (B), and restored MCA flow, with a persistent ACA flow deficit, after reperfusion (C). (D) An angiogram from the same animal during occlusion shows capillary non-perfusion in the lateral portion of the cranial window, presumably delineating the region destined for infarction, as suggested by <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0071478#pone-0071478-g006" target="_blank">Figure 6</a>. (E–F) Regional blood flow was estimated as a function of distance between the MCA and ACA supplied territories. Flow was restored to baseline values on the MCA side after reperfusion, while a flow deficit persisted on the ACA side (E). These changes were not mirrored by the contralateral hemisphere (F). (G–H) Consistent with these results, vessels preferentially dilated in the MCA region, and constricted in the ACA region after reperfusion. (I) Remarkably, even along a single artery, both dilation and constriction were observed, depending on the earlier presence of nearby capillary non-perfusion.</p

OCT angiography suggested remodeling in the border zone during distal MCAO.

<p>Angiograms were acquired over a 1.5 mm x 1.5 mm field-of-view with a transverse resolution of 3.6 µm before (A) and after (B) one week permanent dMCAO. (C–D) Zoomed images show pial collateral growth (solid white arrows), dural vessel dilation (dotted white arrow), and a more irregular capillary bed (green), suggesting angiogenesis.</p

Correlation of acute cellular scattering changes after transient fMCAO with MAP2 immunohistochemistry, approximately two hours after reperfusion.

<p>(A) Coronal section shows a clear delineation of the lesion, with absent MAP2 immunoreactivity. Sagittal OCT cross-sections in the infarct (B) and peri-infarct (C) regions show differences in signal characteristics. (D) When the logarithmic signal change over the first 250 microns of cortical tissue is displayed <i>en face</i>, a clear border is observed, delineating the infarct. The OCT signal characteristics of the contralateral cortex (E–G) are comparable to those of the peri-infarct cortex. (H) Curvature differences, determined from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0071478#pone.0071478.e003" target="_blank">Equation 3</a>, are also observed between infarct and peri-infarct cortical regions, as suggested by <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0071478#pone-0071478-g005" target="_blank">Figure 5</a>. (I–J) Aberrant cortical cellular morphology, visualized approximately 2 hours after reperfusion by Cresyl Violet near the ipsilateral lesion boundary (black arrow), may partially account for the observed scattering changes.</p