Honeycomb blocks composed of carbonate apatite, β-tricalcium phosphate, and hydroxyapatite for bone regeneration: effects of composition on biological responses

Synthetic scaffolds exhibiting bone repair ability equal to that of autogenous bone are required in the fields of orthopedics and dentistry. A suitable synthetic bone graft substitute should induce osteogenic differentiation of mesenchymal stem cells, osteogenesis, and angiogenesis. In this study, three types of honeycomb blocks (HCBs), composed of hydroxyapatite (HAp), β-tricalcium phosphate (TCP), and carbonate apatite (CO3Ap), were fabricated, and the effects of HCB composition on bone formation and maturation were investigated. The HC structure was selected to promote cell penetration and tissue ingrowth. HAp and β-TCP HCBs were fabricated by extrusion molding followed by sintering. The CO3Ap HCBs were fabricated by extrusion molding followed by sintering and dissolution-precipitation reactions. These HCBs had similar macroporous structures: all harbored uniformly distributed macropores (∼160 ​μm) that were regularly arrayed and penetrated the blocks unidirectionally. Moreover, the volumes of macropores were nearly equal (∼0.15 ​cm3/g). The compressive strengths of CO3Ap, HAp, and β-TCP HCBs were 22.8 ​± ​3.5, 34.2 ​± ​3.3, and 24.4 ​± ​2.4 ​MPa, respectively. Owing to the honeycomb-type macroporous structure, the compressive strengths of these HCBs were higher than those of commercial scaffolds with intricate three-dimensional or unidirectional macroporous structure. Notably, bone maturation was markedly faster in CO3Ap HCB grafting than in β-TCP and HAp HCB grafting, and the mature bone area percentages for CO3Ap HCBs at postsurgery weeks 4 and 12 were 14.3- and 4.3-fold higher and 7.5- and 1.4-fold higher than those for HAp and β-TCP HCBs, respectively. The differences in bone maturation and formation were probably caused by the disparity in concentrations of calcium ions surrounding the HCBs, which were dictated by the inherent material resorption behavior and mechanism; generally, CO3Ap is resorbed only by osteoclastic resorption, HAp is not resorbed, and β-TCP is rapidly dissolved even in the absence of osteoclasts. Besides the composition, the microporous structure of HC struts, inevitably generated during the formation of HCBs of various compositions, may contribute to the differences in bone maturation and formation.

TRAF6 maintains mammary stem cells and promotes pregnancy-induced mammary epithelial cell expansion

Receptor activator of nuclear factor (NF)-κB (RANK) signaling promotes pregnancy-dependent epithelial cell differentiation and expansion for mammary gland development, which requires NF-κB pathway-dependent Cyclin D1 induction and inhibitor of DNA binding 2 (Id2) pathway-dependent anti-apoptotic gene induction. However, the roles of tumor necrosis factor receptor-associated factor 6 (TRAF6) remain unclear despite its requirement in RANK signaling. Here we show that TRAF6 is crucial for both mammary stem cell maintenance and pregnancy-induced epithelial cell expansion. TRAF6 deficiency impairs phosphoinositide 3-kinase (PI3K)/AKT and canonical NF-κB pathways, whereas noncanonical NF-κB signaling remains functional. Therefore, we propose that TRAF6 promotes cell proliferation by activating PI3K/AKT signaling to induce retinoblastoma phosphorylation in concert with noncanonical NF-κB pathway-dependent Cyclin D1 induction. Furthermore, TRAF6 inhibits apoptosis by activating canonical NF-κB signaling to induce anti-apoptotic genes with the Id2 pathway. Therefore, proper orchestration of TRAF6-dependent and -independent RANK signals likely establishes mammary gland formation.

Wound-Healing Problems Associated with Combined Vascular Malformations in Klippel-Trenaunay Syndrome

Significance: In Klippel-Trenaunay syndrome (KTS), management of a wound in the affected limb can be difficult because of the underlying vascular malformations present. This review describes the characteristics of KTS with wound complications in light of the genetic and molecular mechanisms of the disease. Recent Advances: KTS is a slow-flow combined vascular malformation characterized by the triad of capillary malformation, venous malformation with or without lymphatic malformation, and limb overgrowth. KTS is encompassed within the phosphatidylinositol-4,5-bisphosphate3-kinase catalytic subunit alpha (PIK3CA)-related overgrowth spectrum (PROS), having recently been linked to activating mutations in the PIK3CA gene. This clearly has implications for both molecular diagnosis and potential treatment strategies for the disease. Critical Issues: KTS should be distinguished from Parkes Weber syndrome, a fast-flow-type combined vascular malformation with limb overgrowth. Individualized management is needed for KTS and should be focused on the treatment of symptoms. Future Directions: Targeted therapies that inhibit the phosphoinositide 3-kinase signaling pathway are a potential treatment option for PROS.

Changes in high endothelial venules in lymph nodes after vascularized and nonvascularized lymph node transfer in a murine autograft model

BACKGROUND AND OBJECTIVES

Vascularized lymph node transfer (LNT) is gaining popularity in the treatment of lymphedema. However, it is unclear whether the vascularization of transferred lymph nodes (LNs) contributes to functional improvement. High endothelial venules (HEVs) are specialized vessels that allow lymphocytes to enter LNs. In this study, we compared the numbers of HEVs and lymphocytes in LNs after vascularized and nonvascularized LNT.

METHODS

Fifty mice were divided into three groups (group 1, pedicled vascularized LNT; group 2, pedicled nonvascularized LNT; group 3, free nonvascularized LNT). Afferent lymphatic reconnection was confirmed by patent blue staining. The transferred LNs were harvested 4 weeks after surgery. HEVs, B-cells, and T-cells were subjected to immunohistochemical staining and quantified.

RESULTS

Afferent lymphatic reconnection was observed in 13 of 20 transferred LNs in group 1, 11 of 15 in group 2, and 7 of 15 in group 3. The ratio of dilated/total HEVs in transferred LNs with afferent lymphatic reconnection was significantly higher in group 1 than in groups 2 and 3. No significant differences in numbers of B-cells and T-cells were found in the transferred LNs.

CONCLUSIONS

We found that more functional HEVs were preserved in cases with successful afferent lymphatic reconnection after vascularized LNT than after nonvascularized LNT.

A method of producing genetically manipulated mouse mammary gland

Background

To obtain a deep understanding of the mechanism by which breast cancer develops, the genes involved in tumorigenesis should be analyzed in vivo. Mouse mammary gland can regenerate completely from a mammary stem cell (MaSC), which enables us to analyze the effect of gene expression and repression on tumorigenesis in mammary gland regenerated from genetically manipulated MaSCs. Although lentiviral and retroviral systems have usually been applied for gene transduction into MaSCs, they are associated with difficulty in introducing long, repeated, or transcriptional termination sequences. There is thus a need for an easier and quicker gene delivery system.

Methods

We devised a new system for gene delivery into MaSCs using the piggyBac transposon vectors and electroporation. Compared with viral systems, this system enables easier and quicker transfection of even long, repeated, or transcriptional termination DNA sequences. We designed gene expression vectors of the transposon system, equipped with a luciferase (Luc) expression cassette for monitoring gene transduction into regenerative mammary gland in mice by in-vivo imaging. A doxycycline (Dox)-inducible system was also integrated for expressing the target gene after mammary regeneration to mimic the actual mechanism of tumorigenesis.

Results

With this new gene delivery system, genetically manipulated mammary glands were successfully reconstituted even though the vector size was > 200 kb and even in the presence of DNA elements such as promoters and transcription termination sequences, which are major obstacles to viral vector packaging. They differentiated correctly into both basal and luminal cells, and showed normal morphological change and milk production after pregnancy, as well as self-renewal capacity. Using the Tet-On system, gene expression can be controlled by the addition of Dox after mammary reconstitution. In a case study using polyoma-virus middle T antigen (PyMT), oncogene-induced tumorigenesis was achieved. The histological appearance of the tumor was highly similar to that of the mouse mammary tumor virus-PyMT transgenic mouse model.

Conclusions

With this system, gene transduction in the mammary gland can be easily and quickly achieved, and gene expression can be controlled by Dox administration. This system for genetic manipulation could be useful for analyzing genes involved in breast cancer.

Electronic supplementary material

The online version of this article (10.1186/s13058-018-1086-8) contains supplementary material, which is available to authorized users.

Feasibility of pedicled vascularized inguinal lymph node transfer in a mouse model: A preliminary study

PURPOSE

Vascularized lymph node transfer is becoming more common in the treatment of lymphedema, but suitable small animal models for research are lacking. Here, we evaluated the feasibility of pedicled vascularized inguinal lymph node transfer in mice.

METHODS

Twenty-five mice were used in the study. An inguinal lymph node-bearing flap with a vascular pedicle containing the superficial caudal epigastric vessels was transferred into the ipsilateral popliteal fossa after excision of the popliteal lymph node. Indocyanine green (ICG) angiography was used to confirm vascularity of the flap. ICG lymphography was performed to evaluate lymphatic flow at 3 and 4 weeks postoperatively. Patent blue dye was injected into the ipsilateral hind paw to observe staining of the transferred lymph node at 4 weeks postoperatively. All transferred lymph nodes were then harvested and histologically evaluated by hematoxylin and eosin staining.

RESULTS

In 16 of the 25 mice, ICG lymphography showed reconnection between the transferred lymph node and the afferent lymphatic vessels, as confirmed by patent blue staining. Histologically, these transferred lymph nodes with afferent lymphatic reconnection significantly regressed in size (0.37 ± 0.24 mm² ) and showed clear follicle formation, whereas those without afferent lymphatic reconnection showed less size regression (1.31 ± 1.17 mm² ); the cell population was too dense to allow identification of follicles.

CONCLUSIONS

We established a mouse model of vascularized lymph node transfer with predictable afferent lymphatic reconnection. Both the vascularization and reconnection might be necessary for functional regeneration of the transferred lymph node.

A highly sensitive trap vector system for isolating reporter cells and identification of responsive genes

We devised a versatile vector system for efficient isolation of reporter cells responding to a certain condition of interest. This system combines nontoxic GAL4-UAS and piggyBac transposon systems, allowing application to mammalian cells and improved expression of a fluorescent reporter protein for cell sorting. Case studies under conditions of c-MYC gene induction or endoplasmic reticulum (ER) stress with thapsigargin on mouse or human cell lines confirmed easy and efficient isolation of responsive reporter cells. Sequence analyses of the integrated loci of the thapsigargin-responsive clones identified responsive genes including BiP and OSBPL9. OSBPL9 is a novel ER stress-responsive gene and we confirmed that endogenous mRNA expression of OSBPL9 is upregulated by thapsigargin, and is repressed by IRE1α inhibitors, 4μ8C and toyocamycin, but not significantly by a PERK inhibitor, GSK2656157. These results demonstrate that this approach can be used to discover novel genes regulated by any stimuli without the need for microarray analysis, and that it can concomitantly produce reporter cells without identification of stimuli-responsive promoter/enhancer elements. Therefore, this system has a variety of benefits for basic and clinical research.

Adjunctive perampanel in partial-onset seizures: Asia-Pacific, randomized phase III study

OBJECTIVES

To evaluate the efficacy, safety, and tolerability of perampanel, a selective, non-competitive, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor antagonist, as an adjunctive treatment for patients with refractory partial-onset seizures (POS) from Asia-Pacific.

MATERIALS & METHODS

This multicenter, randomized, double-blind, placebo-controlled trial (ClinicalTrials.gov identifier: NCT01618695) involved patients aged ≥12 years with refractory POS (receiving 1-3 antiepileptic drugs). Patients were randomized (1:1:1:1) to receive once-daily placebo or perampanel 4, 8, or 12 mg over a 6-week titration and 13-week maintenance double-blind period. Enzyme-inducing antiepileptic drugs were equally stratified between groups. The primary efficacy endpoint was percent change in POS frequency per 28 days (double-blind phase vs baseline). Other efficacy endpoints included ≥50% responder rate and seizure freedom. Treatment-emergent adverse events (TEAEs) were also monitored.

RESULTS

Of 710 randomized patients, seizure frequency data were available for 704 patients. Median percent changes in POS frequency per 28 days indicated dose-proportional reductions in seizure frequency: -10.8% with placebo and -17.3% (P = .2330), -29.0% (P = .0003), and -38.0% (P < .0001) with perampanel 4, 8, and 12 mg, respectively. In total, 108 (15.3%) patients discontinued treatment; 44 (6.2%) due to TEAEs. TEAEs occurring in ≥5% of patients, and reported at least twice as frequently with perampanel vs placebo, included dizziness and irritability.

CONCLUSIONS

Adjunctive perampanel (8 and 12 mg/d) significantly improved seizure control in patients with refractory POS. Safety and tolerability were acceptable at daily doses of perampanel 4-12 mg.

[Intraoperative Artery Wall Stimulating Electromyography during Microvascular Decompression Surgery to Treat Hemifacial Spasm:A Case Report]

OBJECTIVE

Microvascular decompression(MVD)surgery has been established as a standard treatment for hemifacial spasm. However, because decompression surgery results in unfavorable outcomes in some cases, a more critical monitoring strategy is required. To improve surgical outcome for hemifacial spasms, abnormal muscle response(AMR)has been proposed as a tool for intraoperative electrophysiological monitoring during MVD surgery. Here, we report a single case of surgical MVD monitoring using artery wall stimulating electromyography(AWS-EMG). AWS-EMG was developed as a new monitoring method in addition to AMR.

CASE DESCRIPTION

A 60-year-old woman was diagnosed with hemifacial spasm using magnetic resonance imaging and magnetic resonance angiography fusion imaging. We performed MVD surgery using AWS-EMG and AMR. We successfully identified AWS-EMG before decompression and confirmed immediate AWS-EMG loss after decompression. This behavior was consistent with AMR. After surgery, the patient showed no further symptoms of hemifacial spasm.

CONCLUSIONS

In addition to AMR, AWS-EMG might be a promising candidate for intraoperative monitoring for patients with hemifacial spasm.