Vertebral Implantation of NELL-1 Enhances Bone Formation in an Osteoporotic Sheep Model

Comparative population genomics analysis uncovers genomic footprints and genes influencing body weight trait in Chinese indigenous chicken

Body weight of chicken is a typical quantitative trait, which shows phenotypic variations due to selective breeding. Despite some QTL loci have been obtained, the body weight of native chicken breeds in different geographic regions varies greatly, its genetic basis remains unresolved questions. To address this issue, we analyzed 117 Chinese indigenous chickens from 10 breeds (Huiyang Bearded, Xinhua, Hotan Black, Baicheng You, Liyang, Yunyang Da, Jining Bairi, Lindian, Beijing You, Tibetan). We applied fixation index (FST) analysis to find selected genomic regions and genes associated with body weight traits. Our study suggests that NELL1, XYLT1, and NCAPG/LCORL genes are strongly selected in the body weight trait of Chinese indigenous chicken breeds. In addition, the IL1RAPL1 gene was strongly selected in large body weight chickens, while the PCDH17 and CADM2 genes were strongly selected in small body weight chickens. This result suggests that the patterns of genetic variation of native chicken and commercial chicken, and/or distinct local chicken breeds may follow different evolutionary mechanisms.

Exploring the growth trait molecular markers in two sheep breeds based on Genome-wide association analysis

Growth traits are quantitative traits controlled by multiple micro-effect genes. we identified molecular markers related to sheep growth traits, which formed the basis of molecular breeding. In this study, we randomly selected 100 Qira Black sheep and 84 German Merino sheep for the blood collection the jugular vein to genotype by using the Illumina Ovine SNP 50K Bead Chip. quality control criteria for statistical analysis were: rejection detection rate < 90% and minimum allele frequency (MAF) < 5%. Then, we performed Genome-wide association studies (GWAS) on sheep body weight, body height, body length, and chest circumference using mixed linear models. After getting 55 SNPs with significant correlation, they were annotated by reference genome of Ovis aries genome (Oar_v4.0) and We obtained a total of 84 candidate genes associated with production traits (BMPR1B, HSD17B3, TMEM63C, etc.). We selected BMPR1B for population validation and found a correlation between the FecB locus and body weight traits. Therefore, this study not only supplements the existing knowledge of molecular markers of sheep growth traits, but also has important theoretical significance and reference value for the mining of functional genes of sheep growth traits.

NELL1 Regulates the Matrisome to Promote Osteosarcoma Progression

Sarcomas produce an abnormal extracellular matrix (ECM), which in turn provides instructive cues for cell growth and invasion. Neural EGF like-like molecule 1 (NELL1) is a secreted glycoprotein characterized by its nonneoplastic osteoinductive effects, yet it is highly expressed in skeletal sarcomas. Here, we show that genetic deletion of NELL1 markedly reduces invasive behavior across human osteosarcoma (OS) cell lines. NELL1 deletion resulted in reduced OS disease progression, inhibiting metastasis and improving survival in a xenograft mouse model. These observations were recapitulated with Nell1 conditional knockout in mouse models of p53/Rb-driven sarcomagenesis, which reduced tumor frequency and extended tumor-free survival. Transcriptomic and phosphoproteomic analyses demonstrated that NELL1 loss skews the expression of matricellular proteins associated with reduced FAK signaling. Culturing NELL1 knockout sarcoma cells on wild-type OS-enriched matricellular proteins reversed the phenotypic and signaling changes induced by NELL1 deficiency. In sarcoma patients, high expression of NELL1 correlated with decreased overall survival. These findings in mouse and human models suggest that NELL1 expression alters the sarcoma ECM, thereby modulating cellular invasive potential and prognosis. Disruption of NELL1 signaling may represent a novel therapeutic approach to short-circuit sarcoma disease progression.

SIGNIFICANCE

NELL1 modulates the sarcoma matrisome to promote tumor growth, invasion, and metastasis, identifying the matrix-associated protein as an orchestrator of cell-ECM interactions in sarcomagenesis and disease progression.

Genetic and pharmacologic suppression of PPARγ enhances NELL-1-stimulated bone regeneration

Recent investigations into mechanisms behind the development of osteoporosis suggest that suppressing PPARγ-mediated adipogenesis can improve bone formation and bone mineral density. In this study, we investigated a co-treatment strategy to enhance bone formation by combining NELL-1, an osteogenic molecule that has been extensively studied for its potential use as a therapeutic for osteoporosis, with two methods of PPARγ suppression. First, we suppressed PPARγ genetically using lentiviral PPARγ-shRNA in immunocompromised mice for a proof of concept. Second, we used a PPARγ antagonist to suppress PPARγ pharmacologically in immunocompetent senile osteopenic mice for clinical transability. We found that the co-treatment strategy significantly increased bone formation, increased the proliferation stage cell population, decreased late apoptosis of primary mouse BMSCs, and increased osteogenic marker mRNA levels in comparison to the single agent treatment groups. The addition of PPARγ suppression to NELL-1 therapy enhanced NELL-1's effects on bone formation by upregulating anabolic processes without altering NELL-1's inhibitory effects on osteoclastic and adipogenic activities. Our findings suggest that combining PPARγ suppression with therapeutic NELL-1 may be a viable method that can be further developed as a novel strategy to reverse bone loss and decrease marrow adiposity in age-related osteoporosis.

Signaling network regulating osteogenesis in mesenchymal stem cells

Osteogenesis is an important developmental event that results in bone formation. Bone forming cells or osteoblasts develop from mesenchymal stem cells (MSCs) through a highly controlled process regulated by several signaling pathways. The osteogenic lineage commitment of MSCs is controlled by cell-cell interactions, paracrine factors, mechanical signals, hormones, and cytokines present in their niche, which activate a plethora of signaling molecules belonging to bone morphogenetic proteins, Wnt, Hedgehog, and Notch signaling. These signaling pathways individually as well as in coordination with other signaling molecules, regulate the osteogenic lineage commitment of MSCs by activating several osteo-lineage specific transcription factors. Here, we discuss the key signaling pathways that regulate osteogenic differentiation of MSCs and the cross-talk between them during osteogenic differentiation. We also discuss how these signaling pathways can be modified for therapy for bone repair and regeneration.

NELL-1 in Genome-Wide Association Studies across Human Diseases

Neural epidermal growth factor-like (EGFL)-like protein (NELL)-1 is a potent and key osteogenic factor in the development and regeneration of skeletal tissues. Intriguingly, accumulative data from genome-wide association studies (GWASs) have started unveiling potential broader roles of NELL-1 beyond its functions in bone and cartilage. With exploration of the genetic variants of the entire genome in large-scale disease cohorts, GWASs have been used for establishing the connection between specific single-nucleotide polymorphisms of NELL1, in addition to osteoporosis, metabolic diseases, inflammatory conditions, neuropsychiatric diseases, neurodegenerative disorders, and malignant tumors. This review summarizes the findings from GWASs on the manifestation, significance level, implications on function, and correlation of specific NELL1 single-nucleotide polymorphisms in various disorders in humans. By offering a unique and comprehensive correlation between genetic variants and plausible functions of NELL1 in GWASs, this review illustrates the wide range of potential effects of a single gene on the pathogenesis of multiple disorders in humans.

Recent Progresses in the Treatment of Osteoporosis

Osteoporosis (OP) is a chronic bone disease characterized by aberrant microstructure and macrostructure of bone, leading to reduced bone mass and increased risk of fragile fractures. Anti-resorptive drugs, especially, bisphosphonates, are currently the treatment of choice in most developing countries. However, they do have limitations and adverse effects, which, to some extent, helped the development of anabolic drugs such as teriparatide and romosozumab. In patients with high or very high risk for fracture, sequential or combined therapies may be considered with the initial drugs being anabolic agents. Great endeavors have been made to find next generation drugs with maximal efficacy and minimal toxicity, and improved understanding of the role of different signaling pathways and their crosstalk in the pathogenesis of OP may help achieve this goal. Our review focused on recent progress with regards to the drug development by modification of Wnt pathway, while other pathways/molecules were also discussed briefly. In addition, new observations made in recent years in bone biology were summarized and discussed for the treatment of OP.

Application of Enhanced Recovery after Surgical Treatment of the Occipitocervical Region

Objective

The concept of enhanced recovery after surgery (ERAS) has been proposed to provide guidance for the improved postoperative rehabilitation of patients with occipitocervical region disease (ORD).

Methods

This study retrospectively investigated 208 consecutive patients (116 men and 92 women) ranging in age from 22 to 76 years with ORD between July 2014 and June 2017 in our medical center, who were divided into three groups that received different preoperative, intraoperative, and postoperative management plans: traditional group (n = 73), ameliorated group (n = 70), and ERAS group (n = 65). We compiled a range of data relating to demographics and postoperative changes in hemoglobin and albumin, surgery duration, intraoperative blood loss, number of postoperative hospitalization days and expenses, readmission rates, and visual analog scale pain symptoms. Data were statistically evaluated using one‐way analysis of variance with Student–Newman–Keuls‐q post hoc tests or chi‐square tests.

Results

There were no significant differences in terms of age (P = 0.235), gender (P = 0.691), body mass index (P = 0.723), American Society of Anesthesiologists grade (0.747), lesion character (P = 0.337) and lesion site (P = 0.957) between the three groups. Within a 6 months follow‐up period, there was no significant difference between the three groups in terms of surgery duration (P = 0.225), blood loss (P = 0.172), changes in hemoglobin (P = 0.255) and albumin (P = 0.178). However, postoperative hospitalization days (P = 0.000), postoperative costs (P = 0.019) and improvement of pain symptoms (P = 0.000) in ERAS group were significantly lower or higher than those in traditional group or ameliorated group, respectively. There were 29 (39.73%), 22 (31.43%), and 13 (20.00%), recorded cases of postoperative complications in traditional group, ameliorated group and ERAS group, respectively; complications in ERAS group were significantly lower than those in other two groups (P = 0.043). Moreover, all of the complications were mitigated effectively by the infusion of fluid, analgesia, treatment of infections, or antiemetic medications. There were 2 (2.74%), 3 (4.29%) and 2 (3.08%), recorded cases of re‐admission in traditional group, ameliorated group and ERAS group, respectively, but there were no statistically significant differences when compared across the three groups (P = 0.866).

Conclusions

ERAS can provide benefits when it applied to patients undergoing ORD surgery mainly in terms of reducing postoperative complications, however, ERAS does not increase the economic burden of patients or decrease the risk of readmission.

An overview of de novo bone generation in animal models

Some of the earliest success in de novo tissue generation was in bone tissue, and advances, facilitated by the use of endogenous and exogenous progenitor cells, continue unabated. The concept of one health promotes shared discoveries among medical disciplines to overcome health challenges that afflict numerous species. Carefully selected animal models are vital to development and translation of targeted therapies that improve the health and well-being of humans and animals alike. While inherent differences among species limit direct translation of scientific knowledge between them, rapid progress in ex vivo and in vivo de novo tissue generation is propelling revolutionary innovation to reality among all musculoskeletal specialties. This review contains a comparison of bone deposition among species and descriptions of animal models of bone restoration designed to replicate a multitude of bone injuries and pathology, including impaired osteogenic capacity.

Use of Silver Nanoparticle–Gelatin/Alginate Scaffold to Repair Skull Defects

The major objectives of this study were to investigate the effects of silver nanoparticles– gelatin (AgNPs) on the physical and chemical properties of gelatin/alginate (Gel/Alg) scaffolds and the bone-promoting effect of AgNP–Gel/Alg scaffolds. Gel/Alg scaffolds consisting of 0 μM, 200 μM, 400 μM, and 600 μM AgNPs were prepared. SEM was used to evaluate the physical properties of the scaffolds. A CCK-8 assay was performed to determine the cell proliferation activity, and Micro-CT and histological analysis were used to assess the osteogenic effect. The pore size, porosity, and the water absorption and degradation rates of AgNP–Gel/Alg scaffolds were found to be increased compared with those of Gel/Alg scaffolds (control group). CCK-8 showed that cell proliferation activity in the 200 μM group was significantly higher than that in the control group. Micro-CT analysis showed that there was more new bone around AgNP–Gel/Alg than the control group, and the amount of bone formation in the 200 μM group was significantly higher than that in the other groups. Masson staining showed that numerous collagen fibers had proliferated around the AgNP–Gel/Alg scaffold and tended to thicken over time. AgNP–Gel/Alg scaffolds promoted the repair of skull defects in New Zealand rabbits and exerted a marked osteogenic effect in vivo. The 200 μM AgNP–Gel/Alg scaffold was shown to be more suitable for bone tissue engineering materials.

Comparative population genomic analysis uncovers novel genomic footprints and genes associated with small body size in Chinese pony

Background

Body size is considered as one of the most fundamental properties of an organism. Due to intensive breeding and artificial selection throughout the domestication history, horses exhibit striking variations for heights at withers and body sizes. Debao pony (DBP), a famous Chinese horse, is known for its small body size and lives in Guangxi mountains of southern China. In this study, we employed comparative population genomics to study the genetic basis underlying the small body size of DBP breed based on the whole genome sequencing data. To detect genomic signatures of positive selection, we applied three methods based on population comparison, fixation index (F_ST), cross population composite likelihood ratio (XP-CLR) and nucleotide diversity (θπ), and further analyzed the results to find genomic regions under selection for body size-related traits.

Results

A number of protein-coding genes in windows with the top 1% values of F_ST (367 genes), XP-CLR (681 genes), and log₂ (θπ ratio) (332 genes) were identified. The most significant signal of positive selection was mapped to the NELL1 gene, probably underlies the body size and development traits, and may also have been selected for short stature in the DBP population. In addition, some other loci on different chromosomes were identified to be potentially involved in the development of body size.

Conclusions

Results of our study identified some positively selected genes across the horse genome, which are possibly involved in body size traits. These novel candidate genes may be useful targets for clarifying our understanding of the molecular basis of body size and as such they should be of great interest for future research into the genetic architecture of relevant traits in horse breeding program.

Functionalization of Ceramic Coatings for Enhancing Integration in Osteoporotic Bone: A Systematic Review

Background: The success of reconstructive orthopaedic surgery strongly depends on the mechanical and biological integration between the prosthesis and the host bone tissue. Progressive population ageing with increased frequency of altered bone metabolism conditions requires new strategies for ensuring an early implant fixation and long-term stability. Ceramic materials and ceramic-based coatings, owing to the release of calcium phosphate and to the precipitation of a biological apatite at the bone-implant interface, are able to promote a strong bonding between the host bone and the implant. Methods: The aim of the present systematic review is the analysis of the existing literature on the functionalization strategies for improving the implant osteointegration in osteoporotic bone and their relative translation into the clinical practice. The review process, conducted on two electronic databases, identified 47 eligible preclinical studies and 5 clinical trials. Results: Preclinical data analysis showed that functionalization with both organic and inorganic molecules usually improves osseointegration in the osteoporotic condition, assessed mainly in rodent models. Clinical studies, mainly retrospective, have tested no functionalization strategies. Registered trademarks materials have been investigated and there is lack of information about the micro- or nano- topography of ceramics. Conclusions: Ceramic materials/coatings functionalization obtained promising results in improving implant osseointegration even in osteoporotic conditions but preclinical evidence has not been fully translated to clinical applications.

Clinical advantages and disadvantages of anabolic bone therapies targeting the WNT pathway

The WNT signalling pathway is a key regulator of bone metabolism, particularly bone formation, which has helped to define the role of osteocytes - the most abundant bone cells - as orchestrators of bone remodelling. Several molecules involved in the control of the WNT signalling pathway have been identified as potential targets for the development of bone-building therapeutics for patients with osteoporosis. Several of these molecules have been investigated in animal models, but only inhibitors of sclerostin (which is produced by osteocytes) have been investigated in phase III clinical studies. Here, we review the rationale for these developments and the specificity and potential off-target actions of WNT-based therapeutics. We also describe the available preclinical and clinical studies and discuss the benefits and risks of using sclerostin inhibitors for the management of patients with osteoporosis.

Preclinical and Translational Studies in Small Ruminants (Sheep and Goat) as Models for Osteoporosis Research

PURPOSE OF THE REVIEW

This review summarizes research on the use of sheep and goats as large animal models of human osteoporosis for preclinical and translational studies.

RECENT FINDINGS

The most frequent osteoporotic sheep model used is the ovariectomized sheep with 12 months post-operatively or more and the combined treatment of ovariectomized sheep associated to calcium/vitamin D-deficient diet and glucocorticoid applications for 6 months, but other methods are also described, like pinealectomy or hypothalamic-pituitary disconnection in ovariectomized sheep. The goat model for osteoporosis research has been used in a very limited number of studies in osteoporosis research relative to sheep. These osteoporotic small ruminant models are applied for biomaterial research, bone augmentation, efficacy of implant fixation, fragility fracture-healing process improvement, or bone-defect repair studies in the osteopenic or osteoporotic bone. Sheep are a recognized large animal model for preclinical and translational studies in osteoporosis research and the goat to a lesser extent. Recently, the pathophysiological mechanism underlying induction of osteoporosis in glucocorticoid-treated ovariectomized aged sheep was clarified, being similar to what occurs in postmenopausal women with glucocorticoid-induced osteoporosis. It was also concluded that the receptor activator of NF-κB ligand was stimulated in the late progressive phase of the osteoporosis induced by steroids in sheep. The knowledge of the pathophysiological mechanisms at the cellular and molecular levels of the induction of osteoporosis in small ruminants, if identical to humans, will allow in the future, the use of these animal models with greater confidence in the preclinical and translational studies for osteoporosis research.

NELL-1, HMGB1, and CCN2 Enhance Migration and Vasculogenesis, But Not Osteogenic Differentiation Compared to BMP2

Currently, autografts still represent the gold standard treatment for the repair of large bone defects. However, these are associated with donor-site morbidity and increased pain, cost, and recovery time. The ideal therapy would use biomaterials combined with bone growth factors to induce and instruct bone defect repair without the need to harvest patient tissue. In this line, bone morphogenetic proteins (BMPs) have been the most extensively used agents for clinical bone repair, but at supraphysiological doses that are not without risk. Because of the need to eliminate the risks of BMP2 use in vivo, we assessed the ability of three putative osteogenic factors, nel-like molecule type 1 (NELL-1), high mobility group box 1 (HMGB1), and CCN2, to enhance the essential processes for bone defect repair in vitro and compared them to BMP2. Although it has been reported that NELL-1, HMGB1, and CCN2 play a role in bone formation, less is known about the contribution of these proteins to the different events involved, such as cell migration, osteogenesis, and vasculogenesis. In this study, we investigated the effects of different doses of NELL-1, HMGB, CCN2, and BMP2 on these three processes as a model for the recruitment and differentiation of resident cells in the in vivo bone defect repair situation, using cells of human origin. Our data demonstrated that NELL-1, HMGB1, and CCN2 significantly induced mesenchymal stem cell migration (from 1.58-fold increase compared to control), but BMP2 did not. Interestingly, only BMP2 increased osteogenesis in marrow stromal cells, whereas it inhibited osteogenesis in preosteoblasts. Moreover, the four proteins studied promoted significantly endothelial cell migration, reaching a maximum of 2.4-fold increase compared to control, and induced formation of tube-like structures. NELL-1, HMGB1, and CCN2 had these effects at relatively low doses compared to BMP2. This work indicates that NELL-1, HMGB1, and CCN2 might enhance bone defect healing via the recruitment of endogenous cells and induction of vascularization and act via different processes than BMP2.

Neural EGF-like protein 1 (NELL-1): Signaling crosstalk in mesenchymal stem cells and applications in regenerative medicine

Bone tissue regeneration holds the potential to solve both osteoporosis and large skeletal defects, two problems associated with significant morbidity. The differentiation of mesenchymal stem cells into the osteogenic lineage requires a specific microenvironment and certain osteogenic growth factors. Neural EGF Like-Like molecule 1 (NELL-1) is a secreted glycoprotein that has proven, both in vitro and in vivo, to be a potent osteo-inductive factor. Furthermore, it has been shown to repress adipogenic differentiation and inflammation. NELL-1 can work synergistically with other osteogenic factors such as Bone Morphogenic Protein (BMP) -2 and -9, and has shown promise for use in tissue engineering and as a systemically administered drug for the treatment of osteoporosis. Here we provide a comprehensive up-to-date review on the molecular signaling cascade of NELL-1 in mesenchymal stem cells and potential applications in bone regenerative engineering.

Isolation and characterization of canine perivascular stem/stromal cells for bone tissue engineering

For over 15 years, human subcutaneous adipose tissue has been recognized as a rich source of tissue resident mesenchymal stem/stromal cells (MSC). The isolation of perivascular progenitor cells from human adipose tissue by a cell sorting strategy was first published in 2008. Since this time, the interest in using pericytes and related perivascular stem/stromal cell (PSC) populations for tissue engineering has significantly increased. Here, we describe a set of experiments identifying, isolating and characterizing PSC from canine tissue (N = 12 canine adipose tissue samples). Results showed that the same antibodies used for human PSC identification and isolation are cross-reactive with canine tissue (CD45, CD146, CD34). Like their human correlate, canine PSC demonstrate characteristics of MSC including cell surface marker expression, colony forming unit-fibroblast (CFU-F) inclusion, and osteogenic differentiation potential. As well, canine PSC respond to osteoinductive signals in a similar fashion as do human PSC, such as the secreted differentiation factor NEL-Like Molecule-1 (NELL-1). Nevertheless, important differences exist between human and canine PSC, including differences in baseline osteogenic potential. In summary, canine PSC represent a multipotent mesenchymogenic cell source for future translational efforts in tissue engineering.