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Stem cell therapy using mesenchymal stem/stromal cells (MSCs) represents a novel approach to treating severe diseases, including osteoarthritis. However, the therapeutic benefit of MSCs is highly dependent on their differentiation state, which can be regulated by many factors. Herein, three-dimensional (3D) magnetic scaffolds were successfully fabricated by incorporating magnetic nanoparticles (MNPs) into electrospun gelatin nanofibers. When positioned near a rotating magnet (f = 0.5 Hz), the magnetic scaffolds with the embedded MSCs were driven upward/downward in the culture container, which induced mechanical stimulation to MSCs due to spatial confinement and fluid flow. The extracellular matrix-mimicking scaffold and the alternating magnetic field significantly enhanced chondrogenesis instead of osteogenesis. Furthermore, the fiber topography could be tuned with different compositions of the coating layer on MNPs, and the topography had a significant impact on MSC differentiation. Selective up-regulation of chondrogenesis-related genes (COL2A1 and ACAN) was found for the magnetic scaffolds with citric acid-coated MNPs (CAG). In contrast, osteogenesis-related genes (RUNX2 and SPARC) were selectively and significantly up-regulated for the magnetic scaffolds with polyvinylpyrrolidone-coated MNPs. Prior to implantation in vivo, chondrogenic preconditioning of MSCs within the CAG scaffolds under a dynamic magnetic field resulted in superior osteochondral repair. Hence, the magnetic scaffolds together with an in-house rotating magnet device could be a novel platform to initiate multiple stimuli on stem cell differentiation for effective repair of osteochondral defects.

Multiple myeloma (MM) is a haematological malignancy characterised by the clonal proliferation of plasma cells in the bone marrow. More than 80% of patients with MM display evidence of myeloma bone disease (MBD), characterised by the formation of osteolytic lesions throughout the axial and appendicular skeleton. MBD significantly increases the risk of skeletal-related events such as pathologic fracture, spinal cord compression and hypercalcaemia. MBD is the result of MM plasma cells-mediated activation of osteoclast activity and suppression of osteoblast activity. Bisphosphonates (BP), pyrophosphate analogues with high bone affinity, are the only pharmacological agents currently recommended for the treatment and prevention of MBD and remain the standard of care. Pamidronate and zoledronic acid are the most commonly used BP to treat MBD. Although generally safe, frequent high doses of BP are associated with adverse events such as renal toxicity and osteonecrosis of the jaw. As such, optimal duration and dosing of BP therapy is required in order to minimise BP-associated adverse events. The following guidelines provide currently available evidence for the adoption of a tailored approach when using BP for the management of MBD.

Waldenström macroglobulinaemia (WM) is an indolent B-cell malignancy characterised by the presence of immunoglobulin M (IgM) paraprotein and bone marrow infiltration by clonal small B lymphocytes, plasmacytoid lymphocytes and plasma cells. The symptoms of WM are protean, often follow an asymptomatic phase and may include complications related to the paraneoplastic effects of IgM paraprotein. The revised 2016 World Health Organization classification includes the MYD88 L265P mutation, which is seen in90% of cases, within the diagnostic criteria for WM. While treatment of WM has often been considered together with other indolent B cell lymphomas, there are unique aspects of WM management that require specific care. These include the unreliability of IgM and paraprotein measurements in monitoring patients prior to and after treatment, the lack of correlation between disease burden and symptoms and rituximab-induced IgM flare. Moreover, while bendamustine and rituximab has recently been approved for reimbursed frontline use in WM in Australia, other regimens, including ibrutinib- and bortezomib-based treatments, are not funded, requiring tailoring of treatment to the regional regulatory environment. The Medical and Scientific Advisory Group of the Myeloma Foundation Australia has therefore developed clinical practice guidelines with specific recommendations for the work-up and therapy of WM to assist Australian clinicians in the management of this disease.

cDNA expression cloning using retroviral vectors provides a means of stably introducing genes into target cells at efficiencies that surpass those achieved by transfection. Furthermore, retroviral vectors allow for the introduction and expression of complex cDNA libraries in a wide range of cell types, including cells of hemopoietic origin. Here we report a novel method for rapidly isolating genes encoding cell surface molecules (CSM) from a human bone marrow stromal cell cDNA library constructed in the retroviral vector, pRUFneo. With a newly described, highly efficient selection strategy using mAb and Ab-coated magnetic beads, we have successfully isolated six cDNA encoding previously defined CSM, including beta 1 integrin and endoglin. Moreover, we have used this approach to define the gene and hence the CSM identified by three previously unclustered mAb. These results confirm previous studies demonstrating the general utility of retroviral cDNA libraries and further extend their use to the expression cloning of cDNA encoding CSM.

Chronic low-back pain of discal origin is linked strongly to disc degeneration. Current nonsurgical treatments are palliative and fail to restore the disc extracellular matrix. In this study the authors examined the capacity of ovine mesenchymal precursor cells (MPCs) to restore the extracellular matrix of degenerate discs in an ovine model.Three adjacent lumbar discs of 24 adult male sheep were injected intradiscally with chondroitinase-ABC (cABC) to initiate disc degeneration. The remaining lumbar discs were used as normal controls. Three months after cABC injection, the L3-4 discs of all animals were injected with either a high dose (4 × 10(6) cells, in 12 sheep) or low dose (0.5 × 10(6) cells, in 12 sheep) of MPCs suspended in hyaluronic acid (HA). The adjacent L4-5 degenerate discs remained untreated; the L5-6 discs were injected with HA only. The animals were euthanized at 3 or 6 months after MPC injections (6 sheep from each group at each time point), and histological sections of the lumbar discs were prepared. Radiographs and MR images were obtained prior to cABC injection (baseline), 3 months after cABC injection (pretreatment), and just prior to necropsy (posttreatment).Injection of cABC decreased the disc height index (DHI) of target discs by 45%-50%, confirming degeneration. Some recovery in DHI was observed 6 months after treatment in all cABC-injected discs, but the DHI increased to within baseline control values only in the MPC-injected discs. This improvement was accompanied by a reduction in MRI degeneration scores. The histopathology scores observed at 3 months posttreatment for the high-dose MPC-injected discs and at 6 months posttreatment for the low-dose MPC-injected discs were significantly different from those of the noninjected and HA-injected discs (p0.001) but not from the control disc scores.On the basis of the findings of this study, the authors conclude that the injection of MPCs into degenerate intervertebral discs can contribute to the regeneration of a new extracellular matrix.

Hypoxia and hypoxia-inducible factors (HIFs) are implicated in the regulation of normal and malignant hematopoiesis. HIF-1α stabilization makes leukemia stem cells and normal HSC dormant and is necessary to maintain their self-renewal potential. In sharp contrast, HIF-2α, which shares 60% homology with HIF-1a, promotes proliferation of renal clear carcinoma and embryonic stem cells by enhancing expression of oct-4, sox2 and activating c-myc. In this study, we investigated the role of hypoxia and HIF-2α in leukemia. In normal mouse and human bone marrow (BM), HIF-2α mRNA expression was observed predominantly in non-hematopoietic stromal cells, while hematopoietic cells displayed low to undetectable levels. In contrast, HIF-2α mRNA and protein were detected in the BM of moribund NOD/SCID mice engrafted with 3 different human ALL, and in cultured human ALL and AML cell lines, suggesting that HIF-2α is abnormally expressed in leukemic cells. To investigate the potential roles of HIF-2α in leukemic cells, we cloned human HIF-2α cDNA into the MXIE retroviral vector. In a 1st model the GM-CSF-dependent mouse pre-leukemic cell line FDCP1, which does not express HIF-2α, was retrovirally transduced with HIF-2α. HIF-2α provided a significant proliferative advantage to FDCP1 cells in hypoxic or normoxic cultures and reduced GM-CSF dependency. We next transplanted retrovirally transduced FDCP1 cells into non-irradiated syngeneic DBA/2 mice. All recipients of FDCP1 transduced with HIF-2α-MXIE vector succumbed to leukemia by week 28 post-transplantation. In sharp contrast, mice receiving FDCP1 transduced with empty MXIE vector, displayed a leukemia penetrance of only 15% by week 45 (Fig. 1a; p=0.0001 log rank, hazard ratio = 12.28).Fig. 1Percent survival of recipients of (a) FDCP1 cells retrovirally transduced with HIF-2α-MXIE vector or MXIE control empty vector, (b) vavBcl2 HSC transduced with HIF-2α-MXIE vector or MXIE empty vector, and (c) HL60 cells transduced with HIF-2α knocked-down or scrambled control lentiviral vectors.Fig. 1. Percent survival of recipients of (a) FDCP1 cells retrovirally transduced with HIF-2α-MXIE vector or MXIE control empty vector, (b) vavBcl2 HSC transduced with HIF-2α-MXIE vector or MXIE empty vector, and (c) HL60 cells transduced with HIF-2α knocked-down or scrambled control lentiviral vectors. In a 2nd model, HSC from vavBcl2 transgenic mice were transduced with human HIF-2α-containing or empty MXIE retroviral vectors and subsequently transplanted into lethally irradiated wild-type recipients. Transduction of vavBcl2 HSC with HIF-2α resulted in the outgrowth of HIF-2α-expressing B cells which was not observed in recipients of vavBcl2 HSC transduced with empty vector. Consequently recipients of HIF-2α transduced vavBcl2 HSC succumbed more rapidly to spontaneous lymphoma compared to controls (Fig. 1b; p=0.036 log rank, hazard ratio = 2.971, MXIE median survival = 56 weeks, HIF2α median survival = 41 weeks). Finally, HIF-2α was knocked-down in human leukemia cell lines U937 and HL60 using a shRNA lentiviral vector. HIF-2α knock-down resulted in a 2-fold decrease in proliferation in vitro. We next transplanted HL60-HIF-2a shRNA and HL60-scrambled shRNA cells into NOD/SCID/ IL2Rγ-/- (NSG) mice for each group. Notably, all recipients of HL60-HIF-2a shRNA cells succumbed to leukemia significantly later than recipients of HL60-scrambled shRNA cells (Fig. 1c; p= Disclosures: No relevant conflicts of interest to declare.