Relative contributions of implant hydrophilicity and nanotopography to implant anchorage in bone at Early Time Points.

OBJECTIVE: To compare the contributions of implant hydrophilicity and nanotopography on anchorage in bone. The effect of elevated calcium surface chemistry on bone anchorage was also investigated. MATERIALS AND METHODS: A full factorial study design was implemented to evaluate the effects of ultraviolet (UV) light and/or sodium lactate (SL) and discrete crystalline deposition of nanocrystals (DCD) treatments on the osseointegration of dual acid-etched (AE) titanium alloy (Ti6Al4V) and grit blasted and AE (BAE) commercially pure titanium (CpTi) implants. Sodium hydroxide (NaOH)-treated CpTi implants were immersed in simulated body fluid (SBF) to increase calcium surface chemistry. Implants were placed in the femora of Wistar rats and tested using pull-out testing (BAE implants: 5, 9, 14 days) or tensile testing (AE implants: 9 days, NaOH implants: 28 days). RESULTS: Ti6Al4V-AE implants with DCD- and UV-treated surfaces significantly increased bone anchorage compared with untreated Ti6Al4V-AE alloy implants. Pull-out testing of BAE-CpTi implants with the DCD treatment showed increased disruption force values compared with surfaces without the DCD treatment at 5, 9 and 14 days by 4.1N, 13.9N and 15.5N, respectively, and UV-treated implants showed an increase at 14 days by 8.4N. No difference was found between NaOH + SBF and NaOH + H2 O groups. CONCLUSIONS: Bone anchorage of implants was found to be improved by UV-treating implants or nanotopographically complex surfaces. However, implant nanotopography was found to have a greater contribution to the overall bone anchorage and is more consistent compared with the time-dependent nature of the UV treatment.

The most reactive amide as a transition-state mimic for cis-trans interconversion.

1-Azatricyclo[3.3.1.1(3,7)]decan-2-one (3), the parent compound of a rare class of 90°-twisted amides, has finally been synthesized, using an unprecedented transformation. These compounds are of special interest as transition-state mimics for the enzyme-catalyzed cis-trans rotamer interconversion of amides involved in peptide and protein folding and function. The stabilization of the amide group in its high energy, perpendicular conformation common to both systems is shown for the rigid tricyclic system to depend, as predicted by calculation, on its methyl group substitution pattern, making 3 by some way the most reactive known "amide".

Lung Transplant Immunomodulation with Genetically Engineered Mesenchymal Stromal Cells-Therapeutic Window for Interleukin-10.

Lung transplantation results are compromised by ischemia-reperfusion injury and alloimmune responses. Ex vivo lung perfusion (EVLP) is used to assess marginal donor lungs before transplantation but is also an excellent platform to apply novel therapeutics. We investigated donor lung immunomodulation using genetically engineered mesenchymal stromal cells with augmented production of human anti-inflammatory hIL-10 (MSCsIL-10). Pig lungs were placed on EVLP for 6 h and randomized to control (n = 7), intravascular delivery of 20 × 106 (n = 5, low dose) or 40 × 106 human MSCs IL-10 (n = 6, high dose). Subsequently, single-lung transplantation was performed, and recipient pigs were monitored for 3 days. hIL-10 secretion was measured during EVLP and after transplantation, and immunological effects were assessed by cytokine profile, T and myeloid cell characterization and mixed lymphocyte reaction. MSCIL-10 therapy rapidly increased hIL-10 during EVLP and resulted in transient hIL-10 elevation after lung transplantation. MSCIL-10 delivery did not affect lung function but was associated with dose-related immunomodulatory effects, with the low dose resulting in a beneficial decrease in apoptosis and lower macrophage activation, but the high MSCIL-10 dose resulting in inflammation and cytotoxic CD8+ T cell activation. MSCIL-10 therapy during EVLP results in a rapid and transient perioperative hIL-10 increase and has a therapeutic window for its immunomodulatory effects.

Umbilical Cord Stem Cell Lysate: A New Biologic Injectate for the Putative Treatment of Acute Temporomandibular Joint Inflammation.

Objective: To compare in vivo, the acute anti-inflammatory effects of a lysate derived from human umbilical perivascular mesenchymal cells with the cells themselves in both an established hind-paw model of carrageenan-induced inflammation and also in the inflamed temporomandibular joint. Study Design: Human umbilical cord perivascular cells were harvested and cultured in xeno- and serum-free conditions to P3. In addition, P3 cells were used to prepare a proprietary 0.22 micron filtered lysate. First, CD1 immunocompetent mice underwent unilateral hind-paw injections of carrageenan for induction of inflammation, followed immediately by treatment with saline (negative control), 1% cell lysate, or viable cells. The contralateral paw remained un-injected with carrageenan. Paw circumference was measured prior to injections and 48 hr later and myeloperoxidase and TNF-alpha concentrations were measured post-sacrifice in excised tissue. Second, immunocompetent Male Wistar rats underwent unilateral intra-articular temporomandibular (TMJ) injections from the same treatment groups and were sacrificed at 4 and 48 hr post-injection. The contralateral TMJ remained un-injected with carrageenan. Articular tissue and synovial aspirates, from the treated TMJ were obtained for histologic and leukocyte infiltration analyses. Results: The lysate and cell-treated hind-paw demonstrated reduced tissue edema, and significantly lower concentrations of myeloperoxidase and TNF-alpha at 48 hr compared to untreated controls. Treated TMJs demonstrated lower concentrations of leukocytes in the synovium compared to controls and histologic evidence, in the peri-articular tissue, of reduced inflammation. Conclusion: In this preliminary study, both the human umbilical perivascular cells and a highly diluted lysate produced therefrom were anti-inflammatory.

Nanoscale implant anchorage aided by cement line deposition into titanium dioxide nanotubes.

The success of titanium dental implants relies on osseointegration, the load-bearing connection between bone tissue and the device that, in contact osteogenesis, comprises the deposition of bony cement line matrix onto the implant surface. Titanium dioxide nanotubes (NTs) are considered a promising surface for improved osseointegration, yet the mechanisms of cement line integration with such features remains elusive. Herein, we illustrate cement line deposition into NTs on the surface of titanium implants with two underlaying microstructures: a machined surface or a blasted/acid etched surface placed in the tibiae of Wistar rats. After retrieval, scanning electron microscopy of tissue reflected from the implant surface indicated minimal incursion of the cement line matrix into the NTs. To investigate this further, focused ion beam was utilized to prepare cross-sectional samples that could be characterized using scanning transmission electron microscopy. The cement line matrix covered NTs regardless of underlying microstructure, which was further confirmed by elemental analysis. In some instances, cement line infiltration into the NTs was noted, which reveals a mechanism of nanoscale anchorage. This study is the first to demonstrate cement line deposition into titanium NTs, suggesting nano-anchorage as a mechanism for the success of the NT modified surfaces in vivo.

Serum- and xeno-free culture of human umbilical cord perivascular cells for pediatric heart valve tissue engineering.

BACKGROUND: Constructs currently used to repair or replace congenitally diseased pediatric heart valves lack a viable cell population capable of functional adaptation in situ, necessitating repeated surgical intervention. Heart valve tissue engineering (HVTE) can address these limitations by producing functional living tissue in vitro that holds the potential for somatic growth and remodelling upon implantation. However, clinical translation of HVTE strategies requires an appropriate source of autologous cells that can be non-invasively harvested from mesenchymal stem cell (MSC)-rich tissues and cultured under serum- and xeno-free conditions. To this end, we evaluated human umbilical cord perivascular cells (hUCPVCs) as a promising cell source for in vitro production of engineered heart valve tissue. METHODS: The proliferative, clonogenic, multilineage differentiation, and extracellular matrix (ECM) synthesis capacities of hUCPVCs were evaluated in a commercial serum- and xeno-free culture medium (StemMACS™) on tissue culture polystyrene and benchmarked to adult bone marrow-derived MSCs (BMMSCs). Additionally, the ECM synthesis potential of hUCPVCs was evaluated when cultured on polycarbonate polyurethane anisotropic electrospun scaffolds, a representative biomaterial for in vitro HVTE. RESULTS: hUCPVCs had greater proliferative and clonogenic potential than BMMSCs in StemMACS™ (p < 0.05), without differentiation to osteogenic and adipogenic phenotypes associated with valve pathology. Furthermore, hUCPVCs cultured with StemMACS™ on tissue culture plastic for 14 days synthesized significantly more total collagen, elastin, and sulphated glycosaminoglycans (p < 0.05), the ECM constituents of the native valve, than BMMSCs. Finally, hUCPVCs retained their ECM synthesizing capacity after 14 and 21 days in culture on anisotropic electrospun scaffolds. CONCLUSION: Overall, our findings establish an in vitro culture platform that uses hUCPVCs as a readily-available and non-invasively sourced autologous cell population and a commercial serum- and xeno-free culture medium to increase the translational potential of future pediatric HVTE strategies. This study evaluated the proliferative, differentiation and extracellular matrix (ECM) synthesis capacities of human umbilical cord perivascular cells (hUCPVCs) when cultured in serum- and xeno-free media (SFM) against conventionally used bone marrow-derived MSCs (BMMSCs) and serum-containing media (SCM). Our findings support the use of hUCPVCs and SFM for in vitro heart valve tissue engineering (HVTE) of autologous pediatric valve tissue. Figure created with BioRender.com.

Effects of two mesenchymal cell populations on hepatocytes and lymphocytes.

The inflammatory response to liver injury plays an important role in the onset of liver fibrosis, which may ultimately lead to liver failure. The attenuation of inflammation and hepatocyte rescue are, therefore, of the utmost importance for recovery. Mesenchymal stromal cells (MSCs) from adult bone marrow have been shown to rescue hepatocyte function. Here we explore a more plentiful source of neonatal MSCs: human umbilical cord perivascular cells (HUCPVCs). We cocultured HUCPVCs or bone marrow-derived mesenchymal stromal cells (BM-MSCs) with rat hepatocytes or human peripheral blood mononuclear cells in order to identify their effects on hepatocyte functionality and the proliferation of phytohemagglutinin-stimulated peripheral blood mononuclear cells (phaPBMCs). The expression of hepatotrophic factors by both types of MSCs in the presence of hepatocytes and the functional implications of blocking putative MSC anti-inflammatory factors were compared. Both types of MSCs improved albumin secretion, ureagenesis, hepatospecific gene expression, cytochrome P450 (CYP) activity, and functional hepatocyte mass maintenance. However, although HUCPVCs had an improved effect on the maintenance of ureagenesis, BM-MSCs had a strong effect on hepatocyte CYP activity. Additionally, each MSC type differentially expressed putative hepatotrophic factors, whereas phaPBMC proliferation was significantly decreased. Indoleamine 2,3-dioxygenase (IDO) was the main immunosuppressive mechanism used by both types of MSCs, but HUCPVCs exhibited higher expression of programmed death 1 ligands. However, the functional significance of the difference in anti-inflammatory factor expression still remains to be elucidated. Thus, both MSC types can serve as hepatocyte stromal cells and mitigate inflammation with IDO, but they present differences in the manner in which they affect hepatocytes and in the expression of both hepatotrophic and anti-inflammatory factors.

The Sigmoidal Nature of Bone Anchorage.

PURPOSE: The purpose of this study was to show the full evolution of bone anchorage caused by the growth of secondary stability and to determine which empirical model would provide the best quantitative description of this growth. MATERIALS AND METHODS: The retention and anchorage of machined (M), grit-blasted and dual acid etched (BAE), and BAE implants with discrete crystals of calcium phosphate (+DCD) were evaluated with both ex vivo and in vivo methods. Ex vivo evaluation of implant retention was tested by measuring the force required to pull implants out of blood-filled osteotomies formed in bovine bone for up to 1 hour. In vivo measurements of bone anchorage were evaluated by reverse torque testing of implants placed in the proximal metaphysis of rat tibiae up to 28 days after initial placement. Four models were fit to the reverse torque results, and fits were evaluated by Bayesian and Akaike information criteria (BIC and AIC) and analysis of variance (ANOVA). RESULTS: AIC and BIC were 655.53 and 684.78, 472.53 and 512.74, 477.40 and 513.96, and 470.60 and 507.16 for the monomolecular, Richards, Gompertz, and logistic curves, respectively. Comparison of the Richards and logistic curves by analysis of variance (ANOVA) resulted in a P value of .78. A comparison of the three implant types using the logistic curve found that M implants had an earlier inflection point compared with BAE implants (P = .038), and the BAE+DCD implants had the greatest peak anchorage and were significantly greater than both M (P < .0001) and BAE implants (P = .005). CONCLUSION: Bone anchorage was found to follow sigmoidal growth, which was best described by the logistic function. Further comparison of the fit values for the logistic curve shows that both overall anchorage and timing of bone anchorage are influenced by implant surface topography.

Mesenchymal stromal cells mediate a switch to alternatively activated monocytes/macrophages after acute myocardial infarction.

Given the established anti-inflammatory properties of mesenchymal stromal cells (MSCs), we investigated their effect on inflammatory cell infiltration of ischemic cardiac tissue and cardiac function. We employed two types of MSCs, human bone marrow-derived (BM) MSCs and human umbilical cord perivascular cells in an experimental acute myocardial infarction (MI) model with the immune-deficient NOD/SCID gamma null mouse. Cells were infused 48 h after induction of MI and mice assessed 24 h later (72 h after MI) for bone marrow (BM), circulating and cardiac tissue-infiltrating monocytes/macrophages. We showed that in the presence of either MSC type, overall macrophage/monocyte levels were reduced, including pro-inflammatory M1-type macrophages, while the proportion of alternatively activated M2-type macrophages was significantly increased in the circulation and heart but not the BM. Moreover, we found decreased expression of IL-1ß and IL-6, increased IL-10 expression and fewer apoptotic cardiomyocytes without changes in angiogenesis in the infarct area. Fractional shortening was enhanced 2 weeks after cell infusion but was similar to medium controls 16 weeks after MI. In vitro studies showed that BM MSCs increased the frequency of alternatively activated monocytes/macrophages, in part by MSC-mediated secretion of IL-10. Our data suggest a new mechanism for MSC-mediated enhancement of cardiac function, possibly via an IL-10 mediated switch from infiltration of pro-inflammatory to anti-inflammatory macrophages at the infarct site. Additional studies are warranted confirming the role of IL-10 and augmenting the anti-inflammatory effects of MSCs in cardiac regeneration.

The effect of intramedullary reaming on a diaphyseal bone defect of the tibia.

BACKGROUND: The effect of intramedullary reaming on diaphyseal tibial defects has not been examined in the literature. The present aim was to relate the extent of reaming to angiogenesis and bone formation occurring around a critical-sized defect in the tibia for two scenarios, namely, when the bone defect is left empty and when the bone defect is treated with autograft. METHODS: Eleven canines were allocated into two groups, namely, empty (n=5) or iliac crest autograft (n=6). All tibiae were reamed to 7.0 mm and fixed with a 6.5-mm statically locked intramedullary nail after creation of an 8.0-mm diaphyseal defect. The extent of reaming of the canal was dependent on the cross-sectional area of the tibia, because all tibiae were reamed to 7.0 mm. Fluorescent markers were administered at different times: calcein green (6 weeks), xylenol orange (9 weeks), and tetracycline (11 weeks and 14 weeks). Animals were sacrificed at 15 weeks and perfused with a barium compound. Analysis consisted of radiography, micro-computed tomography scan, and histology. RESULTS: Linear regression analysis of percent bone volume and canal area provided a Pearson correlation coefficient of r=0.925 (p=0.025) for empty samples and r=0.244 (p=0.641) for autograft samples. Linear regression analysis of percent vasculature volume and canal area provided a Pearson correlation coefficient of r=0.784 (p=0.117) for empty samples and r=-0.146 (p=0.783) for autograft samples. Bone formation rates were reported as the distance between the fluorescent labels and were less within the endosteum, cortex, and periosteum, with extensive reaming in empty samples. CONCLUSIONS: The results suggest that limited reaming may be beneficial to the acute management of tibial shaft fractures with a bone defect.

New insights into spatio-temporal dynamics of mesenchymal progenitor cell ingress during peri-implant wound healing: Provided by intravital imaging.

Surface topography drives the success of orthopedic and dental implants placed in bone, by directing the biology occurring at the tissue-implant interface. Over the last few decades, striking advancements have been made in the development of novel implant surfaces that enhance bone anchorage to their surfaces through contact osteogenesis: the combination of the two phenomena of recruitment and migration of mesenchymal progenitor cells to the implant surface, and their differentiation into bone-forming cells. While the latter is generally understood, the mechanisms and dynamics underlying the migration and recruitment of such progenitor cells into the wound site have garnered little attention. To address this deficit, we surgically inserted metallic implants with two different surface topographies into the skulls of mice, and then employed real-time spatiotemporal microscopic monitoring of the peri-implant tissue healing to track the ingress of cells. Our results show that nano-topographically complex, in comparison to relatively smooth, implant surfaces profoundly affect recruitment of both endothelial cells, which are essential for angiogenesis, and the mesenchymal progenitor cells that give rise to the reparative tissue stroma. The latter appear concomitantly in the wound site with endothelial cells, from the vascularized areas of the periosteum, and demonstrate a proliferative "bloom" that diminishes with time, although some of these cells differentiate into important stromal cells, pericytes and osteocytes, of the reparative wound. In separate experiments we show, using trajectory plots, that the directionality of migration for both endothelial and perivascular cells can be explained by implant surface dependent release of local cytokine gradients from platelets that would become activated on the implant surfaces during initial blood contact. These findings provide new biological insights into the earliest stages of wound healing, and have broad implications in the application of putative nano-topographically complex biomaterials in many tissue types.

The influence of implant design on the kinetics of osseointegration and bone anchorage homeostasis.

Titanium implants have shown considerable success in terms of achieving quick and long-lasting stability in bone through the process of osseointegration. Further work aims to improve implant success rates by modifying implant design on the nano-, micro-, and macro- scales with the goal of achieving higher levels of bone anchorage more quickly. However, the most frequently used methods of analysis do not investigate bone anchorage as a whole but as a series of discrete points, potentially missing relevant insight which could inform the effects of topography on these 3 scale ranges. Herein we utilize an asymptotic curve fitting method to obtain a biologically relevant description of reverse torque data and compare the anchorage of 12 different implant groups. Implant surface topography had a significant effect on the rate and degree of anchorage achieved during the initial bone formation period of osseointegration but was not found to influence the relative change in anchorage during bony remodeling. Threaded implants significantly decreased the time required to reach peak anchorage compared to non-threaded implants and implants with micro-topographically complex surfaces required greater torque to be removed than implants without such features. Nanotopography increased overall anchorage and decreased the time required to reach peak anchorage but to a lesser degree than microtopography or macrogeometry respectively. The curve fitting method utilized in the present study allows for a more integrated analysis of bone anchorage and permits investigation of osseointegration with respect to time, which may lead to a more targeted approach to implant design.

Effects of Conditioned Medium from Bone Marrow Cells on Human Umbilical Cord Perivascular Cells.

Mesenchymal cells derived from human umbilical cord tissue are attracting increasing attention as a source for cell therapy. However, for applying the same in tissue engineering, it has been shown that the differentiation capacity of mesenchymal stromal cells (MSCs) is influenced by the tissue from which the cells are harvested. Thus, to explore the possibility of increasing the osteogenic capacity of MSCs derived from the perivascular tissue of the human umbilical cord (human umbilical cord perivascular cells, HUCPVCs), we cultured these cells using conditioned medium (CM) derived from cultures of human bone marrow-derived mesenchymal stromal cells (hBMMSCs). However, hBM-CM contains a wide variety of growth factors, the amounts and ratios of which are considered to vary with the cell culture stage. Thus, we aimed to evaluate the effects of hBM-CM derived from different stages of hBMMSC culture on the osteogenic capacity of HUCPVCs. The stages of hBMMSC culture were defined as follows: Stage 1 (mitogenic stage) represented the period from the start of hBMMSC culture to 70% cell confluence; Stage 2 (confluent stage) represented the period from 70% confluence to the initiation of calcified nodule formation; and Stage 3 (calcification stage) represented the period following the initiation of calcified nodule formation. An analysis of growth factors contained in the CM obtained at each stage by enzyme-linked immunosorbent assay showed that insulin-like growth factor 1 (IGF-1) was significantly elevated at Stage 2, whereas vascular endothelial growth factor (VEGF) was significantly elevated at Stage 3. HUCPVCs were cultured using the CM from each of the stages for 1, 2, or 3 weeks. RUNX2 expression was the most upregulated at week 1 and then downregulated in all the groups. The expression of collagen 1 was significantly elevated in Stage 2 HUCs at week 3. Alkaline phosphatase (ALP) activity, ALP, and alizarin staining were higher in Stage 2 HUCs and Stage 3 HUCs. The calcium content was the highest in Stage 2 HUCs. The calcium content of HUCPVC obtained by the method used in this study was six times higher than that reported in the previous study. Collectively, our results show that the CM obtained at Stage 2 was most effective in driving the osteogenic differentiation of HUCPVCs. Impact Statement Mesenchymal stromal cells (MSCs) derived from the perivascular tissue of umbilical cords are promising candidates for regenerative medicine. Because these are able to be differentiated into bone cells, cartilage cells, and adipocytes. The number of MSCs in perivascular tissue (HUCPVCs) is ∼1/300 but the number of HUCPVCs that differentiates into osteogenic cells is quite low. In order to promote osteogenic differentiation of HUCPVCs, we cultured HUCPVCs using conditioned medium collected from human bone marrow-derived mesenchymal stromal cells. Our study suggests that the use of conditioned medium can be effective on inducing osteogenic differentiation of HUCPVCs.

Engineered mesenchymal stromal cell therapy during human lung ex vivo lung perfusion is compromised by acidic lung microenvironment.

Ex vivo lung perfusion (EVLP) is an excellent platform to apply novel therapeutics, such as gene and cell therapies, before lung transplantation. We investigated the concept of human donor lung engineering during EVLP by combining gene and cell therapies. Premodified cryopreserved mesenchymal stromal cells with augmented anti-inflammatory interleukin-10 production (MSCIL-10) were administered during EVLP to human lungs that had various degrees of underlying lung injury. Cryopreserved MSCIL-10 had excellent viability, and they immediately and efficiently elevated perfusate and lung tissue IL-10 levels during EVLP. However, MSCIL-10 function was compromised by the poor metabolic conditions present in the most damaged lungs. Similarly, exposing cultured MSCIL-10 to poor metabolic, and especially acidic, conditions decreased their IL-10 production. In conclusion, we found that "off-the-shelf" MSCIL-10 therapy of human lungs during EVLP is safe and feasible, and results in rapid IL-10 elevation, and that the acidic target-tissue microenvironment may compromise the efficacy of cell-based therapies.

Mesenchymal stromal cells as supportive cells for hepatocytes.

Hepatocytes and hematopoietic stem cells (HSCs) appear to share many of the same requirements for their survival, functionality, and proliferation. This may be due to a shared location during fetal development. Moreover, hepatocytes and HSCs are unable to function, or even survive, without stromal cell support. Bone marrow-derived mesenchymal stromal cells (MSCs) support the proliferation and functionality, not only of HSCs, but also of hepatocytes. Although knowledge of the mechanisms underlying HSCs' support is far more advanced than for hepatocytes, data suggest that many agents important for HSCs also maintain the normal hepatocyte phenotype in vitro. Thus, it is possible that new techniques for the maintenance and expansion of HSCs may also be useful for hepatocytes. Bone marrow-derived MSCs are easily cultured and expanded in vitro, and some data suggest that they are immunoregulatory as well as relatively nonimmunogenic. These observations suggest that allogeneic MSCs may be useful not only in supporting hepatocyte growth and proliferation but also in modulating immune responses such as stellate cell activation.

Mesenchymal stromal cells and their derivatives - putative therapeutics in the management of autoimmune pancreatitis.

Autoimmune pancreatitis, a derivative of chronic pancreatitis, frequently causes acute episodes with clinical symptoms parallel to those of acute pancreatitis. Corticosteroids are effective in the treatment of 90% of autoimmune pancreatitis cases, but for the remaining 10%, options are limited. Due to their significant immunomodulatory capabilities, mesenchymal stromal cells (MSCs) have been proposed as a novel treatment strategy for various immune and inflammatory pathologies including those with autoimmune origins. Here, we not only highlight the most recent MSC live-cell experiments to address acute pancreatitis, but also discuss the opportunities afforded by the emergence of the newly identified field of MSC necrobiology. We conclude that the putative employment of MSC derivatives provides a newer and simpler therapeutic approach that could have significant advantages over the use of cells themselves.

Concise review: The challenges and opportunities of employing mesenchymal stromal cells in the treatment of acute pancreatitis.

To date only small animal models have been employed to assess the effect of mesenchymal stromal cell (MSC) therapy on acute pancreatitis (AP), the most common cause of hospitalization for gastrointestinal diseases worldwide. We outline the challenges inherent in the small animal models of AP. We also point to specific benefits afforded by the adoption of larger animal models. The potential for MSC therapeutics in the treatment of AP was recognized over a decade ago. With sharper focus on the form of AP and development of new MSC delivery routes in larger animals, we believe the challenge can be engaged.

Hyperglycemia compromises Rat Cortical Bone by Increasing Osteocyte Lacunar Density and Decreasing Vascular Canal Volume.

Uncontrolled diabetes is associated with increased risk of bony fractures. However, the mechanisms have yet to be understood. Using high-resolution synchrotron micro-CT, we calculated the changes in the microstructure of femoral cortices of streptozotocin-induced hyperglycemic (STZ) Wistar Albino rats and tested the mechanical properties of the mineralized matrix by nanoindentation. Total lacunar volume of femoral cortices increased in STZ group due to a 9% increase in lacunar density. However, total vascular canal volume decreased in STZ group due to a remarkable decrease in vascular canal diameter (7 ± 0.3 vs. 8.5 ± 0.4 µm). Osteocytic territorial matrix volume was less in the STZ group (14,908 ± 689 µm3) compared with healthy controls (16,367 ± 391 µm3). In conclusion, hyperglycemia increased cellularity and lacunar density, decreased osteocyte territorial matrix, and reduced vascular girth, in addition to decreasing matrix mechanical properties in the STZ group when compared with euglycemic controls.

Isolation, propagation, and characterization of human umbilical cord perivascular cells (HUCPVCs).

Current sources of mesenchymal cells, including bone marrow, fat and muscle, all require invasive procurement procedures, and provide relatively low frequencies of progenitors. Here, we describe the non-invasive isolation, and characterization, of a rich source of mesenchymal progenitor cells, which we call human umbilical cord perivascular cells (HUCPVCs). HUCPVCs show a similar immunological phenotype to bone marrow-derived mesenchymal stromal cells (BM-MSCs), since they are non-alloreactive, exhibit immunosuppression, and significantly reduce lymphocyte activation, in vitro. They present a non-hematopoietic myofibroblastic mesenchymal phenotype (CD45-, CD34-, CD105+, CD73+, CD90+, CD44+, CD106+, 3G5+, CD146+); with a 1:300 frequency at harvest, a short-doubling time, and a clonogenic frequency of >1:3 in culture. Furthermore, in addition to robust quinti-potential differentiation capacity in vitro, HUCPVCs have been shown to contribute to both musculo-skeletal and dermal wound healing in vivo.

Highly diastereoselective desymmetrisation of cyclic meso-anhydrides and derivatisation for use in natural product synthesis.

A new and efficient desymmetrisation of succinic and glutaric cyclic meso-anhydrides is described, providing excellent yields and diastereoselectivities in most cases. Derivatisation of the desymmetrised products is demonstrated by their conversion into mono-protected 1,4-diols. General synthetic utility of the method is established by its application towards a key fragment in the total synthesis of the immunosuppressant antitumour natural product, rapamycin.