Factors promoting neurite outgrowth during deer antler regeneration

Progress of Noncoding RNA Regulating the Growth and Development of Antler Tissue Research

Antler is the secondary sexual characteristic of deer, which develops on the forehead at puberty. It is the only organ that can be regenerated entirely in mammals. Therefore, it is often used as a research model in the field of organ regeneration and wound repair. Many growth factors and proteins play an active role throughout the developmental process of antler regeneration. With the rapid development of sequencing technology, more and more noncoding RNAs (ncRNAs) have been discovered, and the relationship between ncRNA and antler regeneration has gradually become clear. This paper focuses on the research progress of several ncRNAs (including miRNA and lncRNA) in deer antler tissues, which are helpful to reveal the molecular mechanism of deer antler regeneration at the molecular level.

Velvet antler polypeptide-loaded polyvinyl alcohol-sodium alginate hydrogels promote the differentiation of neural progenitor cells in 3D towards oligodendrocytes in vitro

Three-dimensional (3D) culture of neural progenitor cells (NPCs) in hydrogels represents a powerful means for recapitulating neurodevelopment, disease modelling and drug discovery. However, the differentiation of NPCs to oligodendrocytes in 3D scaffolds remains a great challenge. In this study, polyvinyl alcohol (PVA) - sodium alginate (SA) composite hydrogels intended for NPC culture in 3D were fabricated by ionic crosslinking between SA and calcium ions. It was demonstrated that adding PVA to the composite hydrogels resulted in increases in pore size and swelling rate and decreases in elastic moduli as the PVA proportion was enhanced. In addition, the composite hydrogels were biocompatible with mouse NPCs and improved the proliferation of the encapsulated NPCs compared with SA hydrogels. Moreover, when velvet antler polypeptides (VAPs), which were capable of facilitating the differentiation of NPCs to oligodendrocyte fate in 2D, were loaded into PVA-SA hydrogels, NPCs differentiated into neurons, astrocytes and oligodendrocytes, with the presence of VAPs promoting oligodendrogenesis in a dose-dependant manner. The present composite hydrogels provide a suitable scaffold for the construction of neural tissue engineering and neurological disease modelling.

Effects and mechanism of lncRNA-27785.1 that regulates TGF-β1 of Sika deer on antler cell proliferation

Transforming growth factor (TGF-β) plays an important role in the development of deer antlers. The purpose of this study was to investigate the role of long noncoding RNA in the transcriptional regulation of TGF-β1 and its relationship with the proliferation and differentiation of antler chondrocytes. High-throughput sequencing was used to screen lncRNAs related to TGF-β1. Next, the overexpression plasmid and interference sequence of target lncRNA27785.1 were constructed and transfected into chondrocytes. We found that lncRNA27785.1 inhibited the proliferation and migration of chondrocytes and delayed the transition of cells from G1 to S phase. qRT-PCR and Western blot analysis indicated that the overexpression of lncRNA27785.1 may downregulate mRNA and protein expression of TGF-BR2, Smad3, pSmad3, and Smad4. Our findings highlight lncRNA27785.1 as an inhibitor of chondrocytes proliferation and differentiation by negatively regulating the TGF-β/Smad signaling pathway; this implicates an important regulatory role for long noncoding RNA in the regeneration of antler.

Screening and functional identification of lncRNAs in antler mesenchymal and cartilage tissues using high-throughput sequencing

Long non-coding RNA (lncRNA) is a transcription product of the mammalian genome that regulates the development and growth in the body. The present study aimed to analyze the expression dynamics of lncRNA in sika antler mesenchymal and cartilage tissues by high-throughput sequencing. Bioinformatics was applied to predict differentially expressed lncRNAs and target genes and screen lncRNAs and mRNAs related to osteogenic differentiation, cell proliferation, and migration. Finally, the expression of the lncRNAs and target genes were analyzed by qRT-PCR. The results showed that compared to the cartilage tissue, the transcription levels of lncRNA and mRNA, 1212 lncRNAs and 518 mRNAs, in mesenchymal tissue were altered significantly. Thus, a complex interaction network was constructed, and the lncRNA-mRNA interaction network correlation related to osteogenic differentiation, cell proliferation, and migration was analyzed. Among these, the 26 lncRNAs and potential target genes were verified by qRT-PCR, and the results of qRT-PCR were consistent with high-throughput sequencing results. These data indicated that lncRNA promotes the differentiation of deer antler mesenchymal tissue into cartilage tissue by regulating the related osteogenic factors, cell proliferation, and migration-related genes and accelerating the process of deer antler regeneration and development.

Post-transcriptional regulation of miRNA-15a and miRNA-15b on VEGFR gene and deer antler cell proliferation

Background

Deer antler is the only regenerative organ in mammals, the regeneration of antler is not only the regeneration of bone tissue, but also accompanied by the regeneration of nerves, blood vessels and so on. The purpose of the current study was to explore the effect of miRNA-15a and miRNA-15b on the regulation of sika deer vascular endothelial growth factor receptor (VEGFR) during rapid antler growth.

Materials and methods

The VEGFR 3′-UTR was analyzed by bioinformatics software to identify the highly matched miRNAs. After transfected with miRNA mimics, the expression of selected miRNAs were measured by RT-qPCR and the relative expression level of VEGFR protein was detected by Western Blot. Dual-luciferase activity assay was used to determine the target relationship between VEGFR and miRNAs. The cartilage cell proliferation and telomerase activity were measured by MTT kit and TRAP assay, respectively.

Results

The VEGFR 3′-UTR contains a binding site for miRNA-15a and miRNA-15b. Over-expression of miRNA-15a and miRNA-15b, which significantly reduced the expression level of VEGFR protein, inhibited the proliferation of cartilage cells, and decreased the telomerase activity of cartilage cells in vitro.

Conclusion

miRNA-15a and miRNA-15b represent novel regulatory factors of VEGFR expression in deer antler.

Determination of the chemical components and phospholipids of velvet antler using UPLC/QTOF-MS coupled with UNIFI software

Velvet antler, which exhibits immune and growth enhancing effects, is commonly used in a variety of Asian health care products, but its complex components remain unknown. The current study analyzed extracts using ultra-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry in the MS^E mode. Automated detection and data filtering were performed using UNIFI software and peaks were compared with a proprietary scientific library (Traditional Medicine Library; TML). The results obtained using different data processing parameters (including 3D peak detection, target by mass and fragment identification) were evaluated against 87 compounds comprising 1 lignan, 30 terpenoids (including 20 triterpenes), 39 steroids, 8 alkaloids, 4 organic acids and 5 esters in the TML. Using a screening method with a mass accuracy cutoff of ±2 mDa, a retention time cutoff of ±0.2 min, a minimum response threshold of 1,000 counts and an average of 10 false detects per sample analysis, 16 phospholipids were identified in the extracts of velvet antler, three of which were quantified. The results demonstrated that there was 1.07±0.02 µg/g of 1-myristoyl-sn-glycero-3-phosphocholine, 7.05±0.52 ng/g of 1,2-dimyristoyl-sn-glycero-3-phosphocholine and 18.81±0.55 ng/g of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine in velvet antler. The current study successfully identified certain components of velvet antler. Furthermore, the results may provide an experimental basis for further pharmacological and clinical study.

An Aqueous Extract of Herbal Medicine ALWPs Enhances Cognitive Performance and Inhibits LPS-Induced Neuroinflammation via FAK/NF-κB Signaling Pathways

Recent studies have shown that Liuwei Dihuang pills (LWPs) can positively affect learning, memory and neurogenesis. However, the underlying molecular mechanisms are not understood. In the present study, we developed ALWPs, a mixture of Antler and LWPs, and investigated whether ALWPs can affect neuroinflammatory responses. We found that ALWPs (500 mg/ml) inhibited lipopolysaccharide (LPS)-induced proinflammatory cytokine IL-1β mRNA levels in BV2 microglial cells but not primary astrocytes. ALWPs significantly reduced LPS-induced cell-surface levels of TLR4 to alter neuroinflammation. An examination of the molecular mechanisms by which ALWPs regulate the LPS-induced proinflammatory response revealed that ALWPs significantly downregulated LPS-induced levels of FAK phosphorylation, suggesting that ALWPs modulate FAK signaling to alter LPS-induced IL-1β levels. In addition, treatment with ALWPs followed by LPS resulted in decreased levels of the transcription factor NF-κB in the nucleus compared with LPS alone. Moreover, ALWPs significantly suppressed LPS-induced BV2 microglial cell migration. To examine whether ALWPs modulate learning and memory in vivo, wild-type C57BL/6J mice were orally administered ALWPs (200 mg/kg) or PBS daily for 3 days, intraperitoneally injected (i.p.) with LPS (250 μg/kg) or PBS, and assessed in Y maze and NOR tests. We observed that oral administration of ALWPs to LPS-injected wild-type C57BL/6J mice significantly rescued short- and long-term memory. More importantly, oral administration of ALWPs to LPS-injected wild-type C57BL/6J mice significantly reduced microglial activation in the hippocampus and cortex. Taken together, our results suggest that ALWPs can suppress neuroinflammation-associated cognitive deficits and that ALWPs have potential as a drug for neuroinflammation/neurodegeneration-related diseases, including Alzheimer's disease (AD).

Pilose antler polypeptides ameliorates hypoxic-ischemic encephalopathy by activated neurotrophic factors and SDF1/CXCR4 axis in rats

Hypoxic-ischemic encephalopathy (HIE) is a complex condition which is associated with high mortality and morbidity. However, few promising treatments for HIE exist. In the present study, the central objective was to identify the therapeutic effect of pilose antler polypeptides (PAP) on HIE in rats. Sprague-Dawley (SD) rats (14 days old) were used and divided into three groups, including control group, hypoxic-ischemia (HI) group and PAP group. After 21 days of treatment, locomotor activity was improved in PAP-treated rats, brain atrophy was decreased and cerebral edema was mitigated to some extent. Real-time quantitative polymerase chain reaction (RT-qPCR) analysis indicated that PAP administration decreased the expressions of inflammatory cytokines and apoptosis genes in hippocampus compared with HI group. Furthermore, the mRNA expressions of genes related to neurotrophic factors were significantly increased in the hippocampus. In addition, the expressions of oxidative stress markers were all down-regulated after PAP administration. Moreover, PAP up-regulated both the mRNA and protein levels of SDF1 and CXCR4, which may activate the SDF1/CXCR4 axis to moderate brain injury. These results suggest that PAP may be potentially used in the treatment of HIE.

The Effect of Velvet Antler Proteins on Cardiac Microvascular Endothelial Cells Challenged with Ischemia-Hypoxia

Velvet antler (VA) is a precious traditional Chinese medicine that is capable of repeated regeneration. Based on the Chinese medicine theory of coordination the heart and kidneys, VA has been employed to treat heart diseases, including ischemic heart disease, heart failure, and arrhythmia. We examined the effects of VA proteins on primary cardiac microvascular endothelial cells (CMECs) that were subjected to ischemia-hypoxia (IH) to investigate their effects on and mechanism of action in the treatment of ischemic heart disease. Velvet antler proteins (VA-pro) were extracted with water as the solvent, the ultrasonic wave method, and freeze-drying technology; then it was analyzed by Nano LC-MS/MS. In addition, the role of VA-pro in cell viability, proliferation, apoptosis, and mitochondrial membrane potential (MMP) were evaluated by the MTS assay, the EdU assay, the Annexin V-FITC/PI double-staining assay, and the JC-1 assay, respectively. Cell migration were evaluated by the scratch assay and the Transwell assay. The expression of apoptosis-associate proteins, Akt and p-Akt, and tube formation in Matrigel of CMECs were also detected. In total, 386 VA-pro were identified. Our results showed that IH significantly reduced the viability of the CMECs (P < 0.001) and suppressed copies of DNA to hold back CMEC proliferation (P < 0.001). The OD of control group was 1.81 ± 0.08 and IH group OD was 1.25 ± 0.03. After suffering with IH for 46 h, CMECs were 75% less likely to migrate (P < 0.001), and its tubule formation ability and MMP were also decreased (P < 0.001). VA-pro treatment resulted in an improvement in CMECs' viability and proliferation (P < 0.001). Such as, the OD of 0.5, 1, and 2 mg/ml rose to 1.56 ± 0.5, 1.74 ± 0.1 and 1.65 ± 0.1, respectively. Similarly, CMECs' migration (for the scratch assay P < 0.001, for the Transwell assay P < 0.05) and tubule formation (P < 0.05) ability were better after treated with VA-pro. At the same time, the stability of MMP was retained preferably (P < 0.001). 50% apoptosis was induced after CMECs were cultured in IH conditions (P < 0.001), while VA-pro decreased the number of apoptotic cells (P < 0.001). All above results showed that 1 mg/ml VA-pro produced maximum results. Furthermore, the expression of pro-apoptosis proteins was higher, but the expression of anti-apoptosis proteins was lower in the IH group (P < 0.05); VA-pro reversed these changes (P < 0.001). These findings suggest that VA-pro ameliorate CMEC injuries induced by IH via regulating the PI3K/Akt signaling pathway.

Peripheral Nerve Nanoimaging: Monitoring Treatment and Regeneration

Accidental and iatrogenic trauma are major causes of peripheral nerve injury. Healing after nerve injury is complex and often incomplete, which can lead to acute or chronic pain and functional impairment. Current assessment methods for nerve regeneration lack sensitivity and objectivity. There is a need for reliable and reproducible, noninvasive strategies with adequate spatial and temporal resolution for longitudinal evaluation of degeneration or regeneration after injury/treatment. Methods for noninvasive monitoring of the efficacy and effectiveness of neurotherapeutics in nerve regeneration or of neuropathic pain are needed to ensure adequacy and responsiveness to management, especially given the large variability in the patient populations, etiologies, and complexity of nerve injuries. Surrogate biomarkers are needed with positive predictive correlation for the dynamics and kinetics of neuroregeneration. They can provide direct real-time insight into the efficacy and mechanisms of individualized therapeutic intervention. Here, we review the state-of-the-art tools, technologies, and therapies in peripheral nerve injury and regeneration as well as provide perspectives for the future. We present compelling evidence that advancements in nanomedicine and innovation in nanotechnology such as nanotheranostics hold groundbreaking potential as paradigm shifts in noninvasive peripheral nerve imaging and drug delivery. Nanotechnology, which revolutionized molecular imaging in cancer and inflammatory disease, can be used to delineate dynamic molecular imaging signatures of neuroinflammation and neuroregeneration while simultaneously monitoring cellular or tissue response to drug therapy. We believe that current clinical successes of nanotechnology can and should be adopted and adapted to the science of peripheral nerve injury and regeneration.

Evaluation of velvet antler total protein effect on bone marrow‑derived endothelial progenitor cells

Lu Rong, velvet antler (VA), is a traditional Chinese medicine, which is used as a food supplement and therapeutic drug in China, Japan, Russia, New Zealand and Southeast Asia. The regenerative characteristics of VA have resulted in great research interest, particularly regarding the fields of organ grafting and stem cell differentiation. Various VA proteomic studies verified that proteins act as the primary bioactive components of VA. The present study aimed to investigate if VA proteins (VA-pro) influence endothelial progenitor cell (EPC) viability. Various methods have previously been used to investigate VA-pro, including freeze-drying technology, ultrasonic wave methods, high performance liquid chromatography-mass spectrometry, EPCs extraction and culture. Results demonstrated that VA-pro promoted EPCs proliferation and migration, particularly at a concentration of 1 mg/ml. Furthermore, VA-pro increased the activation level of Notch1 intracellular domain and Hes1, and the level of phosphorylated-Akt and phosphorylated-mechanistic target of rapamycin. VA-pro may therefore affect EPC viability via regulation of the Notch and Akt signaling pathways. The present study revealed the effects and potential molecular mechanism of VA-pro on EPCs, and suggested an association between VA regeneration characteristics and the optimization of EPC viability. These findings may contribute to EPC transplantation research and aid in providing a novel treatment method for vascular diseases in the future.

Distribution of BDNF and TrkB isoforms in growing antler tissues of red deer

Antlers are the cranial appendages of deer that regenerate each year. This renewal provides a model to explore molecules involved in mammalian organ regeneration. The cellular distributions of the brain-derived neurotrophic factor (BDNF) and the isoforms of its cognate receptor Trk tyrosine kinase receptor (TrkB) were localized by immunohistochemistry in sections of growing red deer antler. BDNF and TrkB full length were widely expressed in the integument, perichondrium, periosteum and bone. The truncated isoform receptor was particularly evidenced in integument and vascular inner dermis, but very light reaction was observed in cartilage and bone, both at the site of endochondral and intramembranous ossification. These observations were also assessed at transcriptional level by RT-PCR analyses. The highest expression of all genes significantly occurred in chondroprogenitor cells; however the full-length TrkB receptor was down regulated in osteocartilaginous compartments, in which the truncated isoform was up regulated. The truncated isoform is a dominant-negative receptor that inhibits the full length receptor signalling, even if the truncated isoform not only has this function. This study establishes the presence of BDNF and its receptor in the different cellular compartments of growing antler. Their transcripts assessed by RT-PCR indicate a local synthesis of these molecules that may contribute to the modulation of antler growth, acting as autocrine and/or paracrine factors independently of nerve supply. Among the plethora of other molecular signals and growth factors affecting the antler growth, the local production of BDNF and its cognate receptor could be of interest in understanding their role in antler renewal and to delineate the different involvement of the receptor isoforms.

Deer antler regeneration: a stem cell-based epimorphic process

Full regeneration of deer antlers, a bona fide epimorphic process in mammals, is in defiance of the general rule of nature. Revealing the mechanism underlying this unique exception would place us in a better position to promote organ regeneration in humans. Antler regeneration takes place in yearly cycles from its pedicle, a permanent protuberance on the frontal bone. Both growing antlers and pedicles consist of internal (cartilage and bone) and external components (skin, blood vessels, and nerves). Recent studies have demonstrated that the regeneration of both internal and external components relies on the presence of pedicle periosteum (PP). PP cells express key embryonic stem cell markers (Oct4, Nanog, and SOX2) and are multipotent, so are termed antler stem cells. Now it is clear that proliferation and differentiation of PP cells directly forms internal antler components; however, how PP initiates and maintains the regeneration of external antler components is thus far not known. Based on the direct as well as indirect evidence that is presented in this review, I put forward the following hypothesis to address this issue. The full regenerative ability of external antler tissue components is achieved through PP-derived chemical induction and PP-derived mechanical stimulation: the former triggers the regeneration of these external components, whereas the latter drives their rapid elongation. Eventual identification of the putative PP-derived chemical factors would open up a new avenue for devising effective therapies for lesions involving each of these tissue components, be they traumatic, degenerative, or linked to developmental (genetic) anomalies.

Gene expression of axon growth promoting factors in the deer antler

The annual regeneration cycle of deer (Cervidae, Artiodactyla) antlers represents a unique model of epimorphic regeneration and rapid growth in adult mammals. Regenerating antlers are innervated by trigeminal sensory axons growing through the velvet, the modified form of skin that envelopes the antler, at elongation velocities that reach one centimetre per day in the common deer (Cervus elaphus). Several axon growth promoters like NT-3, NGF or IGF-1 have been described in the antler. To increase the knowledge on the axon growth environment, we have combined different gene-expression techniques to identify and characterize the expression of promoting molecules not previously described in the antler velvet. Cross-species microarray analyses of deer samples on human arrays allowed us to build up a list of 90 extracellular or membrane molecules involved in axon growth that were potentially being expressed in the antler. Fifteen of these genes were analysed using PCR and sequencing techniques to confirm their expression in the velvet and to compare it with the expression in other antler and skin samples. Expression of 8 axon growth promoters was confirmed in the velvet, 5 of them not previously described in the antler. In conclusion, our work shows that antler velvet provides growing axons with a variety of promoters of axon growth, sharing many of them with deer's normal and pedicle skin.