Spontaneous Repair Research Articles

Spontaneous Renewal of Pediatric Both-Bone Fracture: Case Report

Severe musculoskeletal injuries, resulting in bone and soft-tissue loss, are often caused by high-energy trauma (i.e. falling from heights and road accidents), and many ultimately lead to extreme limitations in motor functions due to fracture complications or amputations. Traumatic bone injuries are very rare in children and are usually detected following open fractures, and their initial or delayed treatment depends on the conditions of the patient’s soft tissue. Here, a rare case of A 13-year-old male patient was referred to the under study hospital due to a roll over car accident with a crush injury, both-bone fracture of the forearm, and radius defects, and the spontaneous repair of the post-traumatic radius defect healing without delayed intervention is presented.

Surgical outcomes of the endonasal endoscopic approach within a standardized management protocol for repair of spontaneous cerebrospinal fluid rhinorrhea.

Spontaneous CSF leaks are rare, their diagnosis is often delayed, and they can precipitate meningitis. Craniotomy is the historical "gold standard" repair for these leaks. An endonasal endoscopic approach (EEA) offers potentially less invasiveness and lower surgical morbidity than a traditional craniotomy but must yield the same surgical success. A paucity of data exists studying EEA as the primary management for spontaneous CSF leaks. The authors retrospectively reviewed patients undergoing spontaneous CSF rhinorrhea repair at their institution from July 2010 to August 2018. Standardized management includes EEA as first-line treatment, and lumbar puncture (LP) performed 24-48 hours postoperatively. If opening pressure on LP is elevated, CSF diversion or acetazolamide therapy is used as needed. Perioperative lumbar drains are not used. Of 46 patients identified, the most common CSF rhinorrhea etiology was encephalocele (28/46, 60.9%), and the most common location was cribriform/ethmoid (26/46, 56.5%). Forty-three patients underwent EEA alone, and 3 underwent a simultaneous EEA/craniotomy. The most common repair strategy was nasoseptal or other pedicled flaps (18/46, 39.1%). Postoperatively, 15 patients (32.6%) received CSF diversion due to elevated ICP, with BMI > 40 kg/m2 being a significant risk factor (odds ratio 4.35, p = 0.033) for postrepair shunt placement. Twelve patients received acetazolamide therapy for treatment of mildly elevated pressures. The average opening pressure of the shunted group was 36 cm H2O and the average for the acetazolamide-only group was 26 cm H2O. Two patients underwent CSF leak repair revision, one because of progressive fungal sinusitis and the other because of recurrent CSF leak. The mean follow-up duration was 15 months. The paradigm of EEA repair of spontaneous CSF rhinorrhea with postoperative LP to identify undiagnosed idiopathic intracranial hypertension appears to be safe and effective. In the authors' cohort, morbid obesity was statistically associated with the need for postoperative CSF diversion. This has implications for future surgical treatment as obesity levels continue to rise worldwide.

Particulated Cartilage for Chondral and Osteochondral Repair: A Review.

Injuries to articular cartilage have a poor spontaneous repair potential and no gold standard treatment exist. Particulated cartilage, both auto- and allograft, is a promising new treatment method that circumvents the high cost of scaffold- and cell-based treatments. A comprehensive database search on particulated cartilage was performed. Fourteen animal studies have found particulated cartilage to be an effective treatment for cartilage injuries. Many studies suggest that juvenile cartilage has increased regenerative potential compared to adult cartilage. Sixteen clinical studies on 4 different treatment methods have been published. (1) CAIS, particulated autologous cartilage in a scaffold, (2) Denovo NT, juvenile human allograft cartilage embedded in fibrin glue, (3) autologous cartilage chips-with and without concomitant bone grafting, and (4) augmented autologous cartilage chips. Implantation of allogeneic and autologous particulated cartilage provides a low cost and effective treatment alternative to microfracture and autologous chondrocyte implantation. The methods are promising, but large randomized controlled studies are needed.

Translating concepts of neural repair after stroke: Structural and functional targets for recovery.

Stroke is among the most common causes of adult disability worldwide, and its disease burden is shifting towards that of a long-term condition. Therefore, the development of approaches to enhance recovery and augment neural repair after stroke will be critical. Recovery after stroke involves complex interrelated systems of neural repair. There are changes in both structure (at the molecular, cellular, and tissue levels) and function (in terms of excitability, cortical maps, and networks) that occur spontaneously within the brain. Several approaches to augment neural repair through enhancing these changes are under study. These include identifying novel drug targets, implementing rehabilitation strategies, and developing new neurotechnologies. Each of these approaches has its own array of different proposed mechanisms. Current investigation has emphasized both cellular and circuit-based targets in both gray and white matter, including axon sprouting, dendritic branching, neurogenesis, axon preservation, remyelination, blood brain barrier integrity, blockade of extracellular inhibitory signals, alteration of excitability, and promotion of new brain cortical maps and networks. Herein, we review for clinicians recovery after stroke, basic elements of spontaneous neural repair, and ongoing work to augment neural repair. Future study requires alignment of basic, translational, and clinical research. The field continues to grow while becoming more clearly defined. As thrombolysis changed stroke care in the 1990 s and thrombectomy in the 2010 s, the augmentation of neural repair and recovery after stroke may revolutionize care for these patients in the coming decade.

Metallurgical modeling of intergranular HAZ liquation cracking during laser welding newly developed crystallography-dependent aerospace materials. Part I: Spontaneous microcrack repair of microstructure development

Metallurgical modeling of microcrack self-repair during laser welding of nickel-based superalloys has been properly established. Metallurgical mechanism of crystallographic control self-repair intergranular liquation cracking of heat-affected zone (HAZ) through spontaneous feed of interdendrite liquid beneath the surface is proposed. Self-repair of arterial crack network with dendrite substructure of backfill enables crack resistance amelioration and is dependent on alloying element and heat input. Microstructure development and solidification behavior are controlled to minimize the severe liquation cracking near the fusion boundary by optimization of laser welding conditions through numerical analysis. Liquid healing of incipient cracking in the HAZ through available feeding fluid flow due to accessible to weld pool are sensitive to grain size and weld pool geometry to metallurgically suppress liquation crack, stabilize the primary solidification path and improve the weld integrity, simultaneously. It is revealed that optimum low heat input is favored to reduce liquation cracking. Theoretical predictions are in satisfactory agreement with microanalysis of measurement result indirectly. In addition, this metallurgical modeling is also applicable to other nickel-based superalloys with similar metallurgical properties.

Longitudinal assessment of recovery after spinal cord injury with behavioral measures and diffusion, quantitative magnetization transfer and functional magnetic resonance imaging.

Spinal cord injuries (SCIs) are a leading cause of disability and can severely impact the quality of life. However, to date, the processes of spontaneous repair of damaged spinal cord remain incompletely understood, partly due to a lack of appropriate longitudinal tracking methods. Noninvasive, multiparametric magnetic resonance imaging (MRI) provides potential biomarkers for the comprehensive evaluation of spontaneous repair after SCI. In this study in rats, a clinically relevant contusion injury was introduced at the lumbar level that impairs both hindlimb motor and sensory functions. Quantitative MRI measurements were acquired at baseline and serially post-SCI for up to 2 wk. The progressions of injury and spontaneous recovery in both white and gray matter were tracked longitudinally using pool-size ratio (PSR) measurements derived from quantitative magnetization transfer (qMT) methods, measurements of water diffusion parameters using diffusion tensor imaging (DTI) and intrasegment functional connectivity derived from resting state functional MRI. Changes in these quantitative imaging measurements were correlated with behavioral readouts. We found (a) a progressive decrease in PSR values within 2 wk post-SCI, indicating a progressive demyelination at the center of the injury that was validated with histological staining, (b) PSR correlated closely with fractional anisotropy and transverse relaxation of free water, but did not show significant correlations with behavioral recovery, and (c) preliminary evidence that SCI induced a decrease in functional connectivity between dorsal horns below the injury site at 24 h. Findings from this study not only confirm the value of qMT and DTI methods for assessing the myelination state of injured spinal cord but indicate that they may also have further implications on whether therapies targeted towards remyelination may be appropriate. Additionally, a better understanding of changes after SCI provides valuable information to guide and assess interventions.

A Triticum vulgare Extract Exhibits Regenerating Activity During the Wound Healing Process.

IntroductionChronic skin lesions represent a problem of increasing occurrence, mostly due to the global ageing of the world population. Research in skin care and dermatology is constantly looking for new non-invasive solutions, preferably those based on the use of natural certified products, able to accelerate the spontaneous skin repair mechanisms and without altering the skin normal appearance and functionality. The wound healing process in the skin is finely regulated by several factors and orchestrated mechanisms, which modulate the progression and the fitting of different consequent phases, including haemostasis, inflammation, cell proliferation and tissue remodelling. It was previously shown that a patented Triticum vulgare aqueous extract was able to trigger the skin repair process by stimulating new tissue growth and reducing the expression levels of inflammatory mediators, such as IL-6, TNFα, prostaglandin E2, and nitric oxide.MethodsScratch assay was performed in Human Dermal Fibroblasts (HDF). The production of fibronectin was measured by gene expression, protein quantification and localization using specific antibodies in HDF. The polymerization of actin was measured using rhodamin-phalloidin in HDF. The epidermal lipid content was estimated in HaCaT (human spontaneously immortalized keratinocytes) using Nile Red staining and the increasing GBA gene expression and activity was demonstrated by RT-PCR and enzymatic activity assay.ResultsIn the present study, it was demonstrated that the T. vulgare extract enhanced cell migration inducing the synthesis of fibronectin, new actin polymerization and stimulating the expression of the Hyaluronan Synthase 2. Furthermore it improved the restoration of the epidermal barrier stimulating lipid synthesis.ConclusionIn conclusion, we demonstrated that the T. vulgare extract possessed promising potential to be developed as a wound healing promoting agent in skin care and dermatology.

Do Most Patients With a Spontaneous Cerebrospinal Fluid Leak Have Idiopathic Intracranial Hypertension?

The association between cerebrospinal fluid (CSF) leaks at the skull base and raised intracranial pressure (ICP) has been reported since the 1960s. It has been suggested that spontaneous CSF leaks might represent a variant of idiopathic intracranial hypertension (IIH). We review the evidence regarding the association between spontaneous CSF leaks and IIH, and the role of ICP in the pathophysiology of nontraumatic skull base defects. We also discuss the management of ICP in the setting of CSF leaks and IIH. References were identified by searches of PubMed from 1955 to September 2018 with the terms "idiopathic intracranial hypertension" and "cerebrospinal fluid leak." Additional references were identified using the terms "pseudotumor cerebri," "intracranial hypertension," "benign intracranial hypertension," and by hand search of relevant articles. A CSF leak entails the egress of CSF from the subarachnoid spaces of the skull base into the surrounding cavitary structures. Striking overlaps exist regarding demographic, clinical, and radiological characteristics between IIH patients and those with spontaneous CSF leaks, suggesting that some (if not most) of these patients have IIH. However, determining whether a patient with spontaneous CSF leak may have IIH may be difficult, as signs and symptoms of raised ICP may be obviated by the leak. The pathophysiology is unknown but might stem from progressive erosion of the thin bone of the skull base by persistent pulsatile high CSF pressure. Currently, there is no consensus regarding the management of ICP after spontaneous CSF leak repair when IIH is suspected. IIH is becoming more widely recognized as a cause of spontaneous CSF leaks, but the causal relationship remains poorly characterized. Systematic evaluation and follow-up of patients with spontaneous CSF leaks by neuro-ophthalmologists will help clarify the relation between IIH and spontaneous CSF leaks.

Spatiotemporal Expression of 3-B-3(-) and 7-D-4 Chondroitin Sulfation, Tissue Remodeling, and Attempted Repair in an Ovine Model of Intervertebral Disc Degeneration.

Examination of intervertebral disc (IVD) regeneration in an ovine annular lesion model. Sulfation motifs are important functional determinants in glycosaminoglycans (GAGs). Previous studies have correlated 3-B-3(-) and 7-D-4 chondroitin sulfate (CS) motifs in tissues undergoing morphogenetic transition in development. We hypothesize that these motifs may also be expressed in degenerate IVDs and may represent a reparative response. Induction of disc degeneration by 5 mm or 6 × 20 mm lesions in the annulus fibrosus (AF) over 6 or 3 to 6 months postoperation (PO). Tissue sections were stained with toluidine blue-fast green, 3-B-3(-) and 7-D-4 CS-sulfation motifs were immunolocalized in 3-month PO 6 × 20 mm lesion IVDs. Sulfated glycosaminoglycan (GAG), 3-B-3(-), and 7-D-4 epitopes were quantitated by ELISIA (enzyme-linked immunosorbent inhibition assay) in extracts of AF (lesion site and contralateral half) and nucleus pulposus (NP) 0, 3, and 6 months PO. Collagenous overgrowth of lesions occurred in the outer AF. Chondroid metaplasia in ~20% of the 6 × 20 mm affected discs resulted in integration of an outgrowth of NP tissue with the inner AF lamellae preventing propagation of the lesion. 3-B-3(-) and 7-D-4 CS sulfation motifs were immunolocalized in this chondroid tissue. ELISIA quantified CS sulfation motifs demonstrating an increase 3 to 6 months PO in the AF lesion and a reduction in sulfated GAG not evident in the contralateral AF. (1) Outer annular lesions underwent spontaneous repair. (2) Chondroid metaplasia of the inner 6 × 20 mm defect prevented its propagation suggesting an apparent reparative response.

The effect of suture techniques used in repair of episiotomy and perineal tear on perineal pain and dyspareunia

It was aimed to determine the effect of continuous technique for repair of episiotomy and spontaneous tear repair compared to interrupted suture technique for perineal pain and dyspareunia. The research was completed with the total 56 cases. It was found in the research that continuous suture technique used in the perineal trauma repair resulted in less perineal pain, less analgesia need, better wound healing, shorter repair time, less material use during rest and daily activities in the early postpartum period compared to the interrupted suture technique. There was no significant difference between groups in terms of having dyspareunia.

An [18F]-Positron Emitting Fluorophore Allows Safe Evaluation of Small Molecule Distribution in the CSF, CSF Fistulas, and CNS Device Placement.

The small molecule fluorescein is commonly used to guide the repair of cerebral spinal fluid leaks (CSFLs) in the clinic. We modified fluorescein so that it is also visible by positron emission tomography (PET). This probe was used to quantitatively track the fast distribution of small molecules in the CSF of rats. We tested this probe in models relevant to the clinical diagnosis and treatment of central nervous system (CNS) diseases that affect CSF flow. In this study, fluorescein was radiolabeled with fluorine-18 to produce Fc-AMBF3. [18/19F]-Fc-AMBF3 was introduced at trace quantities (13.2 nmols, 100 μCi) intrathecally (between L5 and L6) in rats to observe the dynamic distribution and clearance of small molecules in the CSF by both [18F]-PET and fluorescence (FL) imaging. Murine models were used to demonstrate the following utilities of Fc-AMBF3: (1) utility in monitoring the spontaneous CSFL repair of a compression fracture of the cribriform plate and (2) utility in quantifying CSF flow velocity during neurosurgical lumboperitoneal shunt placement. Fc-AMBF3 clearly delineated CSF-containing volumes based on noninvasive PET imaging and in ex vivo FL histology. In vivo morbidity (n = 16 rats, <2.7 mg/kg, 77 times the PET dose) was not observed. The clearance of the contrast agent from the CNS was rapid and quantitative (t1/2 = 33.8 ± 0.6 min by FL and t1/2 = 26.0 ± 0.5 min by PET). Fc-AMBF3 was cleared from the CSF through the vasculature and/or lymphatic system that supplies the cribriform plate and the temporal bone. Fc-AMBF3 can be used to diagnose CSFLs, image CSFL repair, and determine the CSF flow velocity in the CNS or through lumboperitoneal shunts by PET/FL imaging. In conclusion, Fc-AMBF3 PET imaging has been demonstrated to safely and dynamically quantitate CSF flow, diagnose fistulas associated with the CSF space, and approximate the clearance of small molecules in the CSF.

Mesenchymal stem cells for cartilage regeneration in dogs.

Articular cartilage damage and osteoarthritis (OA) are common orthopedic diseases in both humans and dogs. Once damaged, the articular cartilage seldom undergoes spontaneous repair because of its avascular, aneural, and alymphatic state, and the damage progresses to a chronic and painful situation. Dogs have distinctive characteristics compared to other laboratory animal species in that they share an OA pathology with humans. Dogs can also require treatment for naturally developed OA; therefore, effective treatment methods for OA are desired in veterinary medicine as well as in human medicine. Recently, interest has grown in regenerative medicine that includes the use of mesenchymal stem cells (MSCs). In cartilage repair, MSCs are a promising therapeutic tool due to their self-renewal capacity, ability to differentiate into cartilage, potential for trophic factor production, and capacity for immunomodulation. The MSCs from dogs (canine MSCs; cMSCs) share various characteristics with MSCs from other animal species, but they show some deviations, particularly in their differentiation ability and surface epitope expression. In vivo studies of cMSCs have demonstrated that intraarticular cMSC injection into cartilage lesions results in excellent hyaline cartilage regeneration. In clinical situations, cMSCs have shown great therapeutic effects, including amelioration of pain and lameness in dogs suffering from OA. However, some issues remain, such as a lack of regulations or guidelines and a need for unified methods for the use of cMSCs. This review summarizes what is known about cMSCs, including their in vitro characteristics, their therapeutic effects in cartilage lesion treatment in preclinical in vivo studies, their clinical efficacy for treatment of naturally developed OA in dogs, and the current limitations of cMSC studies.

The attempt of spontaneous repair of rotator cuff tear: The role of periostin

The development of a periostin-rich microenvironment in areas associated with insult, orchestrating pathways of repair and rebuilding, is documented. Literature lacks information regarding the presence of periostin in the context of rotator cuff tear (RCT).55 consecutive patients with RCT were enrolled. Immunohistochemical periostin detection was performed on tissue samples excised from tear margins.Our study documented the presence of periostin in the margins of RCT. It is plausible that, when a tear occurs, multiple stimuli, both mechanical and inflammatory, lead to the development of a periostin-rich microenvironment as an attempt to tendon healing.

Vesicular Glutamatergic Transmission in Noise-Induced Loss and Repair of Cochlear Ribbon Synapses.

Noise-induced excitotoxicity is thought to depend on glutamate. However, the excitotoxic mechanisms are unknown, and the necessity of glutamate for synapse loss or regeneration is unclear. Despite absence of glutamatergic transmission from cochlear inner hair cells in mice lacking the vesicular glutamate transporter-3 (Vglut3KO ), at 9-11 weeks, approximately half the number of synapses found in Vglut3WT were maintained as postsynaptic AMPA receptors juxtaposed with presynaptic ribbons and voltage-gated calcium channels (CaV1.3). Synapses were larger in Vglut3KO than Vglut3WT In Vglut3WT and Vglut3+/- mice, 8-16 kHz octave-band noise exposure at 100 dB sound pressure level caused a threshold shift (∼40 dB) and a loss of synapses (>50%) at 24 h after exposure. Hearing threshold and synapse number partially recovered by 2 weeks after exposure as ribbons became larger, whereas recovery was significantly better in Vglut3WT Noise exposure at 94 dB sound pressure level caused auditory threshold shifts that fully recovered in 2 weeks, whereas suprathreshold hearing recovered faster in Vglut3WT than Vglut3+/- These results, from mice of both sexes, suggest that spontaneous repair of synapses after noise depends on the level of Vglut3 protein or the level of glutamate release during the recovery period. Noise-induced loss of presynaptic ribbons or postsynaptic AMPA receptors was not observed in Vglut3KO , demonstrating its dependence on vesicular glutamate release. In Vglut3WT and Vglut3+/-, noise exposure caused unpairing of presynaptic ribbons and presynaptic CaV1.3, but not in Vglut3KO where CaV1.3 remained clustered with ribbons at presynaptic active zones. These results suggest that, without glutamate release, noise-induced presynaptic Ca2+ influx was insufficient to disassemble the active zone. However, synapse volume increased by 2 weeks after exposure in Vglut3KO , suggesting glutamate-independent mechanisms.SIGNIFICANCE STATEMENT Hearing depends on glutamatergic transmission mediated by Vglut3, but the role of glutamate in synapse loss and repair is unclear. Here, using mice of both sexes, we show that one copy of the Vglut3 gene is sufficient for noise-induced threshold shift and loss of ribbon synapses, but both copies are required for normal recovery of hearing function and ribbon synapse number. Impairment of the recovery process in mice having only one functional copy suggests that glutamate release may promote synapse regeneration. At least one copy of the Vglut3 gene is necessary for noise-induced synapse loss. Although the excitotoxic mechanism remains unknown, these findings are consistent with the presumption that glutamate is the key mediator of noise-induced synaptopathy.

Gas-foamed poly(lactide-co-glycolide) and poly(lactide-co-glycolide) with bioactive glass fibres demonstrate insufficient bone repair in lapine osteochondral defects.

Deep osteochondral defects may leave voids in the subchondral bone, increasing the risk of joint structure collapse. To ensure a stable foundation for the cartilage repair, bone grafts can be used for filling these defects. Poly(lactide-co-glycolide) (PLGA) is a biodegradable material that improves bone healing and supports bone matrix deposition. We compared the reparative capacity of two investigative macroporous PLGA-based biomaterials with two commercially available bone graft substitutes in the bony part of an intra-articular bone defect created in the lapine femur. New Zealand white rabbits (n=40) were randomized into five groups. The defects, 4mm in diameter and 8mm deep, were filled with neat PLGA; a composite material combining PLGA and bioactive glass fibres (PLGA-BGf); commercial beta-tricalcium phosphate (β-TCP) granules; or commercial bioactive glass (BG) granules. The fifth group was left untreated for spontaneous repair. After three months, the repair tissue was evaluated with X-ray microtomography and histology. Relative values comparing the operated knee with its contralateral control were calculated. The relative bone volume fraction (∆BV/TV) was largest in the β-TCP group (p≤0.012), which also showed the most abundant osteoid. BG resulted in improved bone formation, whereas defects in the PLGA-BGf group were filled with fibrous tissue. Repair with PLGA did not differ from spontaneous repair. The PLGA, PLGA-BGf, and spontaneous groups showed thicker and sparser trabeculae than the commercial controls. We conclude that bone repair with β-TCP and BG granules was satisfactory, whereas the investigational PLGA-based materials were only as good as or worse than spontaneous repair.

Disruption of RAB-5 Increases EFF-1 Fusogen Availability at the Cell Surface and Promotes the Regenerative Axonal Fusion Capacity of the Neuron.

Following a transection injury to the axon, neurons from a number of species have the ability to undergo spontaneous repair via fusion of the two separated axonal fragments. In the nematode Caenorhabditis elegans, this highly efficient regenerative axonal fusion is mediated by epithelial fusion failure-1 (EFF-1), a fusogenic protein that functions at the membrane to merge the two axonal fragments. Identifying modulators of axonal fusion and EFF-1 is an important step toward a better understanding of this repair process. Here, we present evidence that the small GTPase RAB-5 acts to inhibit axonal fusion, a function achieved via endocytosis of EFF-1 within the injured neuron. Therefore, we find that perturbing RAB-5 activity is sufficient to restore axonal fusion in mutant animals with decreased axonal fusion capacity. This is accompanied by enhanced membranous localization of EFF-1 and the production of extracellular EFF-1-containing vesicles. These findings identify RAB-5 as a novel regulator of axonal fusion in C. elegans hermaphrodites and the first regulator of EFF-1 in neurons.SIGNIFICANCE STATEMENT Peripheral and central nerve injuries cause life-long disabilities due to the fact that repair rarely leads to reinnervation of the target tissue. In the nematode Caenorhabditis elegans, axonal regeneration can proceed through axonal fusion, whereby a regrowing axon reconnects and fuses with its own separated distal fragment, restoring the original axonal tract. We have characterized axonal fusion and established that the fusogen epithelial fusion failure-1 (EFF-1) is a key element for fusing the two separated axonal fragments back together. Here, we show that the small GTPase RAB-5 is a key cell-intrinsic regulator of the fusogen EFF-1 and can in turn regulate axonal fusion. Our findings expand the possibility for this process to be controlled and exploited to facilitate axonal repair in medical applications.

Abstract 57: Exosomes Derived From Ischemic Cerebral Endothelial Cells Promote Axonal Growth

Axonal remodeling is a critical aspect of spontaneous brain repair after stroke. Stroke activates cerebral endothelial cells (CECs) in ischemic blood vessels. Communications between activated CECs and axonal remodeling in ischemic brain have not been fully investigated. Exosomes play vital roles in intercellular communication. We investigated the effect of exosomes derived from CECs harvested from vessels of ischemic rat brains (isCEC-exos) on axonal growth of cortical neurons. Application of isCEC-exos into axons of the neurons cultured in a microfluidic device which separates axons from their somata resulted in significant (p&lt;0.05, n=45 axons) increases of axonal growth (982±24 μm) compared to CEC-exos derived from non-ischemic vessels (nCEC-exos, 793±19 μm). nCEC-exos significantly enhanced axonal growth compared to non-treatment (567±14 μm). Axonal internalization of CEC-exos was confirmed by tracking GFP-exosomes. qRT-PCR and miRNA PCR array analysis revealed that compared to nCEC-exos, &gt;50 mature miRNAs were enriched within isCEC-exos, including miR-19a. Axonal application of isCEC-exos elevated these miRNAs and their pre-miRNAs in axons and somata (from 21 to 85 folds, n=3, p&lt;0.01) compared to non-treated group. Because CEC-exos do not contain the precursor form of miRNAs, these data suggest that CEC-exos transfer their mature miRNAs into distal axons, which triggered increases in precursor and mature miRNAs in distal axons and somata. Moreover, compared to the non-treated group, Western blot analysis (n=3/group) showed that axonal application of isCEC-exos locally reduced axonal growth inhibitory proteins, PTEN (~90%), Sema6A (~75%), and RhoA (~99%), which was inversely associated with increased miRNAs that target these proteins. Furthermore, transient blockage of ribosome translocation with emetine, a protein synthesis inhibitor, in axons abolished the effect of isCEC-exos on distal axonal growth and on alteration of miRNAs and their target proteins. Collectively, our data demonstrate that isCEC-exos internalized by distal axons facilitate axonal growth by altering miRNAs and their target protein profiles in recipient neurons, and these exosomes may potentially provide a therapeutic means to enhance axonal growth.

Endodontic Infection–induced Inflammation Resembling Osteomyelitis of the Jaws in Toll-like Receptor 2/Interleukin 10 Double-knockout Mice

IntroductionIn general, mice develop chronic and nonhealing periapical lesions after endodontic infection. Surprisingly, we recently found that toll-like receptor 2 (TLR2)/interleukin 10 (IL-10) double-knockout (dKO) mice exhibited acute but resolving osteomyelitislike inflammation. In this study, we examined the kinetics of endodontic infection–induced inflammation in TLR2/IL-10 dKO mice and explored a potential mechanism of periapical wound healing mediated by the hypoxia-inducible factor 1 alpha (HIF-1α) subunit and arginase 1. MethodsTLR2/IL-10 dKO and wild-type C57BL/6J mice were subjected to endodontic infection in the mandibular first molars. Mice were sacrificed on days 0 (noninfected), 10, and 21 postinfection. The extent of bone destruction, inflammation, bone deposition, and gene expression were determined by micro–computed tomographic imaging, histology, bone polychrome labeling, and microarray analysis. In addition, the effect of blocking endogenous HIF-1α was tested in infected TLR2/IL-10 dKO mice using the specific inhibitor YC-1. ResultsInfected TLR2/IL-10 dKO mice exhibited extensive bone destruction and inflammation on day 10 followed by spontaneous periapical wound healing including bone formation and resolution of inflammation by day 21 postinfection. In contrast, WT mice developed increasing chronic periapical inflammation over the 21-day observation period. Gene expression analyses and immunohistochemistry revealed that HIF-1α and arginase 1 were up-regulated in spontaneous wound healing in TLR2/IL-10 dKO mice. Blocking of HIF-1α in TLR2/IL-10 dKO mice using YC-1 resulted in significant inhibition of regenerative bone formation. ConclusionsThe TLR2/IL-10 dKO mouse is a novel model resembling osteomyelitis of the jaws in which HIF-1α and arginase 1 appear to be crucial factors in spontaneous wound healing and bone repair.

ErbB receptor signaling directly controls oligodendrocyte progenitor cell transformation and spontaneous remyelination after spinal cord injury.

We recently discovered a novel role for neuregulin‐1 (Nrg1) signaling in mediating spontaneous regenerative processes and functional repair after spinal cord injury (SCI). We revealed that Nrg1 is the molecular signal responsible for spontaneous functional remyelination of dorsal column axons by peripheral nervous system (PNS)‐like Schwann cells after SCI. Here, we investigate whether Nrg1/ErbB signaling controls the unusual transformation of centrally derived progenitor cells into these functional myelinating Schwann cells after SCI using a fate‐mapping/lineage tracing approach. Specific ablation of Nrg1‐ErbB receptors in central platelet‐derived growth factor receptor alpha (PDGFRα)‐derived lineage cells (using PDGFRαCreERT2/Tomato‐red reporter mice crossed with ErbB3fl/fl/ErbB4fl/fl mice) led to a dramatic reduction in P0‐positive remyelination in the dorsal columns following spinal contusion injury. Central myelination, assessed by Olig2 and proteolipid protein expression, was unchanged. Loss of ErbB signaling in PDGFRα lineage cells also significantly impacted the degree of spontaneous locomotor recovery after SCI, particularly in tests dependent on proprioception. These data have important implications, namely (a) cells from the PDGFRα‐expressing progenitor lineage (which are presumably oligodendrocyte progenitor cells, OPCs) can differentiate into remyelinating PNS‐like Schwann cells after traumatic SCI, (b) this process is controlled by ErbB tyrosine kinase signaling, and (c) this endogenous repair mechanism has significant consequences for functional recovery after SCI. Thus, ErbB tyrosine kinase receptor signaling directly controls the transformation of OPCs from the PDGFRα‐expressing lineage into PNS‐like functional remyelinating Schwann cells after SCI.

Active compounds and molecular targets of Chinese herbal medicine for neurogenesis in stroke treatment: Implication for cross talk between Traditional Chinese Medicine and Biomedical Sciences

Neural stem/progenitor cells (NSCs) could be attractive therapeutic targets for promoting adult neurogenesis, brain plasticity, and repair in stroke and neurodegenerative diseases, raising great potentials for regeneration therapy. In adult ischemic brains, NSCs have limited capacities of growth, differentiation, and generating new neurons for repairing the damaged central nervous system. However, the spontaneous brain repair seems to be insufficient to recover neurological deficits in most stroke cases. To overcome those problems, pharmacological manipulations targeting on endogenous NSCs or transplanted stem cells could be a promoting strategy for regeneration therapy. Chinese herbal medicine has great potentials for developing novel therapeutic strategies for adult neurogenesis and brain repair in poststroke treatment. Chinese herbal medicine has a long history for poststroke treatment. Recent studies create great opportunity for drug discovery for promoting neurogenesis and improving the recovery of neurological functions in poststroke treatment. Many active compounds or extracts from medicinal herbs have shown promising effects on regulating proliferation, self-renewal and differentiation of NSCs, and promoting neural network formation as well as neurological functional recovery with in vitro and in vivo experimental evidence. Therefore, targeting neural stem/progenitor cells can be an important opportunity for the studies of Traditional Chinese Medicine in regeneration medicine. Due to the complex interactions of herbal ingredients in network regulation, huge challenge remains to be resolved for further study.