Mesenchymal stem cell exosomes in bone regenerative strategies-a systematic review of preclinical studies.

The ability of bone for regeneration has long been recognized. However, once beyond a critical size, spontaneous regeneration of bone is limited. Several studies have focused on enhancing bone regeneration by applying mesenchymal stromal/stem cells (MSCs) in the treatment strategies. Despite the therapeutic efficacy of MSCs in bone regeneration, cell-based therapies are impeded by several challenges in maintaining the optimal cell potency and viability during expansion, storage, and final delivery to patients. Recently, there has been a paradigm shift in therapeutic mechanism of MSCs in tissue repair from one based on cellular differentiation and replacement to one based on secretion and paracrine signaling. Among the broad spectrum of trophic factors, extracellular vesicles â€‹particularly the exosomes have been reported to be therapeutically efficacious in several injury/disease indications, including bone defects and diseases. The current systematic review aims to summarize the results of the existing animal studies which were conducted to evaluate the therapeutic efficacy of MSC exosomes for bone regeneration. Following the Preferred Reporting Items for Systematic Reviews and Meta-analysis â€‹guidelines, the PubMed and The Cochrane Library database were searched for relevant controlled preclinical animal studies. A total of 23 studies were identified, with the total sample size being 690 rats or mice and 38 rabbits. Generally, MSC exosomes were found to be efficacious for bone regeneration in animal models of bone defects and diseases such as osteonecrosis and osteoporosis. In these studies, MSC exosomes promoted new bone formation with supporting vasculature â€‹and displayed improved morphological, biomechanical, and histological outcomes, coupled with positive effects on cell survival, proliferation, and migration, osteogenesis, and angiogenesis. Unclear-to-low risk in bias and incomplete reporting in the primary studies highlighted the need for standardization in outcome measurements and reporting. Further studies in large animal models to establish the safety and efficacy would provide useful information on guiding the design of clinical trials.

Autologous bone marrow clot as an alternative to autograft for bone defect healing.

OBJECTIVES: Long bone defects often require surgical intervention for functional restoration. The 'gold standard' treatment is autologous bone graft (ABG), usually from the patient's iliac crest. However, autograft is plagued by complications including limited supply, donor site morbidity, and the need for an additional surgery. Thus, alternative therapies are being actively investigated. Autologous bone marrow (BM) is considered as a candidate due to the presence of both endogenous reparative cells and growth factors. We aimed to compare the therapeutic potentials of autologous bone marrow aspirate (BMA) and ABG, which has not previously been done. METHODS: We compared the efficacy of coagulated autologous BMA and ABG for the repair of ulnar defects in New Zealand White rabbits. Segmental defects (14 mm) were filled with autologous clotted BM or morcellized autograft, and healing was assessed four and 12 weeks postoperatively. Harvested ulnas were subjected to radiological, micro-CT, histological, and mechanical analyses. RESULTS: Comparable results were obtained with autologous BMA clot and ABG, except for the quantification of new bone by micro-CT. Significantly more bone was found in the ABG-treated ulnar defects than in those treated with autologous BMA clot. This is possibly due to the remnants of necrotic autograft fragments that persisted within the healing defects at week 12 post-surgery. CONCLUSION: As similar treatment outcomes were achieved by the two strategies, the preferred treatment would be one that is associated with a lower risk of complications. Hence, these results demonstrate that coagulated BMA can be considered as an alternative autogenous therapy for long bone healing.Cite this article: Z. X. H. Lim, B. Rai, T. C. Tan, A. K. Ramruttun, J. H. Hui, V. Nurcombe, S. H. Teoh, S. M. Cool. Autologous bone marrow clot as an alternative to autograft for bone defect healing. Bone Joint Res 2019;8:107-117. DOI: 10.1302/2046-3758.83.BJR-2018-0096.R1.

Ancestral whole-genome duplication in the marine chelicerate horseshoe crabs.

This corrects the article DOI: 10.1038/hdy.2015.89.

Exosomes derived from human embryonic mesenchymal stem cells promote osteochondral regeneration.

OBJECTIVE: Clinical and animal studies have demonstrated the efficacy of mesenchymal stem cell (MSC) therapies in cartilage repair. As the efficacy of many MSC-based therapies has been attributed to paracrine secretion, particularly extracellular vesicles/exosomes, we determine here if weekly intra-articular injections of human embryonic MSC-derived exosomes would repair and regenerate osteochondral defects in a rat model. METHODS: In this study, osteochondral defects were created on the trochlear grooves of both distal femurs in 12 adult rats. In each animal, one defect was treated with 100 µg exosomes and the contralateral defect treated with phosphate buffered saline (PBS). Intra-articular injections of exosomes or PBS were administered after surgery and thereafter weekly for a period of 12 weeks. Three unoperated age-matched animals served as native controls. Analyses were performed by histology, immunohistochemistry, and scoring at 6 and 12 weeks after surgery. RESULTS: Generally, exosome-treated defects showed enhanced gross appearance and improved histological scores than the contralateral PBS-treated defects. By 12 weeks, exosome-treated defects displayed complete restoration of cartilage and subchondral bone with characteristic features including a hyaline cartilage with good surface regularity, complete bonding to adjacent cartilage, and extracellular matrix deposition that closely resemble that of age-matched unoperated control. In contrast, there were only fibrous repair tissues found in the contralateral PBS-treated defects. CONCLUSION: This study demonstrates for the first time the efficacy of human embryonic MSC exosomes in cartilage repair, and the utility of MSC exosomes as a ready-to-use and 'cell-free' therapeutic alternative to cell-based MSC therapy.

Ancestral whole-genome duplication in the marine chelicerate horseshoe crabs.

Whole-genome duplication (WGD) results in new genomic resources that can be exploited by evolution for rewiring genetic regulatory networks in organisms. In metazoans, WGD occurred before the last common ancestor of vertebrates, and has been postulated as a major evolutionary force that contributed to their speciation and diversification of morphological structures. Here, we have sequenced genomes from three of the four extant species of horseshoe crabs-Carcinoscorpius rotundicauda, Limulus polyphemus and Tachypleus tridentatus. Phylogenetic and sequence analyses of their Hox and other homeobox genes, which encode crucial transcription factors and have been used as indicators of WGD in animals, strongly suggests that WGD happened before the last common ancestor of these marine chelicerates >135 million years ago. Signatures of subfunctionalisation of paralogues of Hox genes are revealed in the appendages of two species of horseshoe crabs. Further, residual homeobox pseudogenes are observed in the three lineages. The existence of WGD in the horseshoe crabs, noted for relative morphological stasis over geological time, suggests that genomic diversity need not always be reflected phenotypically, in contrast to the suggested situation in vertebrates. This study provides evidence of ancient WGD in the ecdysozoan lineage, and reveals new opportunities for studying genomic and regulatory evolution after WGD in the Metazoa.

Repair of segmental ulna defects using a ß-TCP implant in combination with a heparan sulfate glycosaminoglycan variant.

Given the wide spread clinical use of ceramic-based bone void fillers, we sought to determine the efficacy of an FDA-approved ß-tricalcium phosphate bone graft substitute (JAX™) in combination with a carboxymethyl cellulose (CMC) handling agent that included a particular heparan glycosaminoglycan (GAG) variant, herein referred to as HS3. Having recently demonstrated efficacy of a combination collagen/HS3 device, we further aimed to determine the support that HS3 could offer a handling agent used to administer a more tissue-relevant bone void filler. This study evaluated the JAX™-HS3 combination device in 1.5 cm critical-sized defects in the ulna bones of 27 male New Zealand White rabbits. Treatment groups consisted of JAX™ applied with CMC alone, or JAX™ with CMC containing either 30 µg or 100 µg of the HS3 GAG. Data based on radiographic, µCT, mechanical, and histological analyses at 4 and 8 weeks post-surgery, clearly demonstrate enhanced new bone formation in the JAX™-HS3 combination treated defects compared to treatment with JAX™ alone. The efficacy of such a combination advocates for inclusion of HS3 in handling agents used in the preparation of various bone void fillers being used in orthopaedic surgery. STATEMENT OF SIGNIFICANCE: Synthetic bone grafts and demineralized bone matrices are gaining prominence as alternatives to autologous and allogeneic bone grafts and are frequently administered in granular form, necessitating their combination with a handling agent. Typical handling agents include glycerol, gelatin, cellulose, hyaluronic acid and lecithin, formulated as hydrogels, which can be further enhanced by the addition of heparan sulfate (HS) glycosaminoglycans that augment the osteostimulatory properties of the graft. Here we assessed the efficacy of ß-TCP granules combined with a hydrogel consisting of carboxymethyl cellulose and the HS variant (HS3) previously shown to enhance osteogenic healing. The data advocates for HS3 to be included during the formulation of hydrogel-based carriers that support the various bone void fillers being used in orthopaedic surgery.

Affinity-selected heparan sulfate for bone repair.

Bone morphogenetic protein (BMP)-2 is a potent bone healing compound produced at sites of bone trauma. Here we present a therapeutic strategy to harness the activity of endogenously produced BMP-2 by delivery of an affinity-matched heparan sulfate (HS) glycos aminoglycan biomaterial that increases the bioavailability, bioactivity and half-life of this growth factor. We have developed a robust, cost effective, peptide-based affinity platform to isolate a unique BMP-2 binding HS variant from commercially available preparations of HS, so removing the manufacturing bottleneck for their translation into the clinic. This affinity-matched HS enhanced BMP-2-induced osteogenesis through improved BMP-2 kinetics and receptor modulation, prolonged pSMAD signaling and reduced interactions with its antagonist noggin. When co-delivered with a collagen implant, the HS was as potent as exogenous BMP-2 for the healing of critical-sized bone defects in rabbits. This affinity platform can be readily tuned to isolate HS variants targeted ata range of clinically-relevant growth and adhesive factors.

Enhancement of meniscal repair in the avascular zone using mesenchymal stem cells in a porcine model.

We hypothesised that meniscal tears treated with mesenchymal stem cells (MSCs) together with a conventional suturing technique would show improved healing compared with those treated by a conventional suturing technique alone. In a controlled laboratory study 28 adult pigs (56 knees) underwent meniscal procedures after the creation of a radial incision to represent a tear. Group 1 (n = 9) had a radial meniscal tear which was left untreated. In group 2 (n = 19) the incision was repaired with sutures and fibrin glue and in group 3, the experimental group (n = 28), treatment was by MSCs, suturing and fibrin glue. At eight weeks, macroscopic examination of group 1 showed no healing in any specimens. In group 2 no healing was found in 12 specimens and incomplete healing in seven. The experimental group 3 had 21 specimens with complete healing, five with incomplete healing and two with no healing. Between the experimental group and each of the control groups this difference was significant (p < 0.001). The histological and macroscopic findings showed that the repair of meniscal tears in the avascular zone was significantly improved with MSCs, but that the mechanical properties of the healed menisci remained reduced.

Annelids in evolutionary developmental biology and comparative genomics.

Annelids have had a long history in comparative embryology and morphology, which has helped to establish them in zoology textbooks as an ideal system to understand the evolution of the typical triploblastic, coelomate, protostome condition. In recent years there has been a relative upsurge in embryological data, particularly with regard to the expression and function of developmental control genes. Polychaetes, as well as other annelids such as the parasitic leech, are now also entering the age of comparative genomics. All of this comparative data has had an important impact on our views of the ancestral conditions at various levels of the animal phylogeny, including the bilaterian ancestor and the nature of the annelid ancestor. Here we review some of the recent advances made in annelid comparative development and genomics, revealing a hitherto unsuspected level of complexity in these ancestors. It is also apparent that the transition to a parasitic lifestyle leads to, or requires, extensive modifications and derivations at both the genomic and embryological levels.

Mesenchymal stem cells in musculoskeletal tissue engineering: a review of recent advances in National University of Singapore.

A key factor in the tissue engineering approach to tissue repair and regeneration is the use of appropriate cells. Mesenchymal stem cells (MSCs) are derived from bone marrow stroma or connective tissues and they have the potential to differentiate into various mesenchymal cell lines in vitro and in vivo. These cells hold great promise for musculoskeletal tissue engineering. This review is based mainly on the work which has been done in the National University of Singapore on the use of MSCs for engineering cartilage, growth plate, bone and tendon/ligament as well as the clinical trail of autologous chondrocyte implantation. It can help to shape future research on musculoskeletal tissue engineering.

Pulmonary function and scoliosis in children with spinal muscular atrophy types II and III.

AIMS: The objectives were to evaluate the clinical course of spinal muscular atrophy (SMA) types II and III patients necessitating scoliosis surgery at the National University Hospital, Singapore. METHODS: A retrospective review of SMA types II and III patients, born over a 10-year period between 1983 and 1992, was conducted. RESULTS: There were eight patients: four with SMA type II and four with SMA type III. The mean age at scoliosis surgery was 9 years 7 months (range 7 years 6 months-12 years 4 months). The mean preoperative Cobb angle was 65.4 degrees (range 43-90 degrees ) and the mean postoperative Cobb angle was 22.6 degrees (range 12-45 degrees ), with a mean correction of 64.8% (range 47.7-77.8%). The decline in percentage predicted forced vital capacity (FVC) was 7.7% (95% CI: 12.4% to 3.0%) per year preoperatively and this was reduced to 3.8% (95% CI: 5.8% to 1.9%) per year postoperatively. The mean length of preoperative and postoperative lung function follow-up was 6.3 months (range 0.03-31 months) and 44 months (range 0-110 months), respectively. CONCLUSIONS: This study suggests that pulmonary function in SMA types II and III continues to decline after scoliosis surgery, though the rate of decline is less marked. Overall, the combined results from this study and all other previously published studies are conflicting in regard to the effect of scoliosis surgery on pulmonary function in SMA types II and III, though half of the studies (3 of 6) did demonstrate a continued decline in lung function postoperatively. This decline in pulmonary function despite spinal stabilization is likely secondary to the progressive neuromuscular weakness of the disease.

Spinal fusion and instrumentation for paediatric neuromuscular scoliosis: retrospective review.

PURPOSE: A retrospective study was conducted to review the surgical results among 24 patients with neuromuscular scoliosis, who were treated with spinal instrumentation and fusion at the Department of Orthopaedic Surgery, National University Hospital, Singapore between March 1993 and December 1998. METHODS: We examined complete hospital records of patients who had scoliosis due to aetiologies such as spinal muscular atrophy, cerebral palsy, Duchenne muscular dystrophy, and congenital myopathies. The mean age of patients was 10.6 years (range, 6-14 years) and the mean follow-up duration was 5.5 years. RESULTS: 18 patients had posterior surgery alone, whereas 4 had an anterior release with posterior instrumentation, and 2 had an anterior fusion with instrumentation. The mean length of stay in the intensive care unit was 2 days and the mean duration of hospital stay was 11 days. The mean correction in scoliosis angle ranged from 75.6 degrees to 25.7 degrees. All patients could at least sit without support postoperatively. The one-second forced expiratory volume and forced vital capacity were, in general, maintained throughout the follow-up. There were 2 major complications and 2 minor ones; these were pseudarthrosis with rod breakage requiring revision, deep infection necessitating hardware removal, superficial infection that responded to antibiotics, and urinary tract infection requiring 3 weeks of antibiotic treatment. There were no deaths or any neurological complications after instrumentation. CONCLUSION: Spinal stabilisation and fusion in children with neuromuscular scoliosis is a safe and effective treatment modality. The effect of surgery on long-term pulmonary function, however, remains controversial and needs to be addressed.

In vitro antigenotoxic activity of novel ginseng saponin metabolites formed by intestinal bacteria.

Ginseng saponin metabolites produced by human intestinal bacteria were evaluated for antigenotoxic properties by testing their effects on benzo[a]pyrene (B[a]P)-induced mutagenicity and clastogenicity. They include 20-O-(beta-D-glucopyranosyl)-20(S)-protopanaxadiol (IH-901), 20-O-(alpha-D-arabinopyranosyl(1-->6)-beta-D-glucopyranosyl]- 20(S)-protopanaxadiol (IH-902) and 20-O-[alpha-D-arabinofuranosyl(1-->6)-beta-D-glucopyranosyl]-20(S)- protopanaxadiol (IH-903). IH-901, IH-902 and IH-903 inhibited the mutagenicity of B[a]P in a dose-dependent manner. In the chromosome aberration assay, IH-901 and IH-903 reduced the frequency of chromosome aberration induced by B[a]P. These results suggest that the ginseng saponin metabolites tested in the present study have potential as chemopreventive agents.

Biomechanical study of tibialis anterior tendon transfer.

The tibialis anterior tendon transfer has been used in the treatment of recurrent congenital clubfoot and paralytic equinovarus foot deformities in cerebral palsy. This study attempts to determine the optimal site of tibialis anterior tendon insertion for ankle and foot motion and to compare the split and whole tendon transfer. Ten fresh normal anatomic leg specimens were used. The lateral half of the tibialis anterior tendon was detached from its insertion, passed beneath the extensor retinaculum, and anchored to the appropriate tarsal bone by a barbed staple. Tension was applied, and ankle and foot motions were measured. The experiment was done by anchoring the tendon to the tarsal bones along the axis of the second metatarsal and serially through to the axis of the fifth' metatarsal. The entire experiment was repeated using the whole tibialis anterior tendon. For split tendon transfer, insertion onto the fourth metatarsal axis was the most effective route; it produced maximal dorsiflexion with minimal supination and pronation. For whole tendon transfer, the ideal site of insertion was along the third metatarsal axis. However, the difference between the average maximum dorsiflexion achieved by the split tendon transfer and that of total tendon transfer is not statistically significant.

The Singapore operation for recurrent dislocation of peroneal tendons: long-term results.

Recurrent dislocation of peroneal tendons is uncommon and there are few reports of the long-term results after repair. The Singapore operation, first described in 1985, is an anatomical repair based on the Bankart-like lesion seen in the superior peroneal retinaculum. We reviewed 21 patients after a mean follow-up of 9.3 years, and found no recurrence. Eighteen had good functional results and had returned to their previous levels of vocational and sports activities. The three fair results were due to painful scars or neuromas.