Potential of thermoresponsive hydrogel as an alternative therapy for rat knee osteoarthritis.

Osteoarthritis is a degenerative condition that is highly prevalent and primarily affects the joints. The knee is the most commonly affected site, impacting the lives of over 300 million individuals worldwide. This study presents a potential solution to address the unmet need for a minimally invasive technique in the treatment of osteoarthritis: a biocompatible, injectable, and thermoresponsive hydrogel. In comparison to commercially available products such as lyophilized platelets, dextrose, and triamcinolone, the thermoresponsive hydrogel exhibits significantly superior performance in dynamic behaviors, including print area, stability, and step cycle, when tested on rats with knee osteoarthritis. However, it demonstrates similar treatment efficacy to these products in static behaviors, as observed through histopathological and immunohistochemical analysis. Therefore, the thermoresponsive hydrogel holds promise as an effective alternative therapy for osteoarthritis. Moreover, by blending the hydrogel with drugs, controlled and sustained release can be achieved, thereby facilitating the long-term management of osteoarthritis symptoms.

Safety and efficacy of intracoronary artery administration of human bone marrow-derived mesenchymal stem cells in STEMI of Lee-Sung pigs-A preclinical study for supporting the feasibility of the OmniMSC-AMI phase I clinical trial.

Background: This study tested whether early left intracoronary arterial (LAD) administration of human bone marrow-derived mesenchymal stem cells (hBMMSCs, called OmniMSCs) in acute ST-segment elevation myocardial infarction (STEMI) of Lee-Sung pigs induced by 90 min balloon-occluded LAD was safe and effective. Methods and results: Young male Lee-Sung pigs were categorized into SC (sham-operated control, n = 3), AMI-B (STEMI + buffer/21 cc/administered at 90 min after STEMI, n = 6), and AMI-M [acute myocardial infarction (AMI) + hBMMSCs/1.5 × 107/administered at 90 min after STEMI, n = 6] groups. By 2 and 5 months after STEMI, the cardiac magnetic resonance imaging demonstrated that the muscle scar score (MSS) and abnormal cardiac muscle exercise score in the infarct region were significantly increased in the AMI-B than in the SC group that were significantly reversed in the AMI-M group, whereas the left ventricular ejection function by each month (from 1 to 5) displayed an opposite pattern of MSS among the groups (all p < 0.001). By 5 months, histopathological findings of infarct and fibrosis areas and isolectin-B4 exhibited an identical pattern, whereas the cellular expressions of troponin-I/troponin-T/von Willebrand factor exhibited an opposite pattern of MSS among the groups (all p < 0.001). The ST-segment resolution (>80%) was significantly earlier (estimated after 6-h AMI) in the AMI-M group than in the AMI-B group (p < 0.001). The protein expressions of inflammation (IL-1ß/TNF-α/NF-κB)/oxidative stress (NOX-1/NOX-2/oxidized protein)/apoptosis (cleaved caspase-3/cleaved PARP)/DNA damage (γ-H2AX) displayed an identical pattern to MSS among the groups, whereas the protein expressions of angiogenesis factors (SDF-1α/VEGF) were significantly and progressively increased from SC, AMI-B, to AMI-M groups (all p < 0.001). Conclusion: Early intra-LAD transfusion of OmniMSC treatment effectively reduced the infarct size and preserved LV function in porcine STEMI.

Biocompatibility and Biological Performance of Additive-Manufactured Bioabsorbable Iron-Based Porous Interference Screws in a Rabbit Model: A 1-Year Observational Study.

This study evaluated the mid-term (12-month) biomechanical, biocompatibility, and biological performance of additive-manufactured bioabsorbable iron-based interference screws (ISs). Two bioabsorbable iron IS types-manufactured using pure iron powder (iron_IS) and using pure iron powder with 0.2 wt% tricalcium phosphate (TCP_IS)-were compared with conventional metallic IS (control) using in vitro biocompatibility and degradation analyses and an in vivo animal study. The in vitro ultimate failure strength was significantly higher for iron_IS and TCP_IS than for control ISs at 3 months post-operatively; however, the difference between groups were nonsignificant thereafter. Moreover, at 3 months after implantation, iron_IS and TCP_IS increased bone volume fraction, bone surface area fraction, and percent intersection surface; the changes thereafter were nonsignificant. Iron_IS and TCP_IS demonstrated degradation over time with increased implant surface, decreased implant volume, and structure thickness; nevertheless, the analyses of visceral organs and biochemistry demonstrated normal results, except for time-dependent iron deposition in the spleen. Therefore, compared with conventional ISs, bioabsorbable iron-based ISs exhibit higher initial mechanical strength. Although iron-based ISs demonstrate high biocompatibility 12 months after implantation, their corrosive iron products may accumulate in the spleen. Because they demonstrate mechanical superiority along with considerable absorption capability after implantation, iron-based ISs may have potential applications in implantable medical-device development in the future.

Correction: Liu et al. 3D-Printed Double-Helical Biodegradable Iron Suture Anchor: A Rabbit Rotator Cuff Tear Model Materials 2022, 15, 2801.

In the original publication [...].

3D-Printed Double-Helical Biodegradable Iron Suture Anchor: A Rabbit Rotator Cuff Tear Model.

Suture anchors are extensively used in rotator cuff tear surgery. With the advancement of three-dimensional printing technology, biodegradable metal has been developed for orthopedic applications. This study adopted three-dimensional-printed biodegradable Fe suture anchors with double-helical threads and commercialized non-vented screw-type Ti suture anchors with a tapered tip in the experimental and control groups, respectively. The in vitro study showed that the Fe and Ti suture anchors exhibited a similar ultimate failure load in 20-pound-per-cubic-foot polyurethane foam blocks and rabbit bone. In static immersion tests, the corrosion rate of Fe suture anchors was 0.049 ± 0.002 mm/year. The in vivo study was performed on New Zealand white rabbits and SAs were employed to reattach the ruptured supraspinatus tendon. The in vivo ultimate failure load of the Fe suture anchors was superior to that of the Ti suture anchors at 6 weeks. Micro-computed tomography showed that the bone volume fraction and bone surface density in the Fe suture anchors group 2 and 6 weeks after surgery were superior, and the histology confirmed that the increased bone volume around the anchor was attributable to mineralized osteocytes. The three-dimensional-printed Fe suture anchors outperformed the currently used Ti suture anchors.

Biocompatibility and Biological Performance Evaluation of Additive-Manufactured Bioabsorbable Iron-Based Porous Suture Anchor in a Rabbit Model.

This study evaluated the biocompatibility and biological performance of novel additive-manufactured bioabsorbable iron-based porous suture anchors (iron_SAs). Two types of bioabsorbable iron_SAs, with double- and triple-helical structures (iron_SA_2_helix and iron_SA_3_helix, respectively), were compared with the synthetic polymer-based bioabsorbable suture anchor (polymer_SAs). An in vitro mechanical test, MTT assay, and scanning electron microscope (SEM) analysis were performed. An in vivo animal study was also performed. The three types of suture anchors were randomly implanted in the outer cortex of the lateral femoral condyle. The ultimate in vitro pullout strength of the iron_SA_3_helix group was significantly higher than the iron_SA_2_helix and polymer_SA groups. The MTT assay findings demonstrated no significant cytotoxicity, and the SEM analysis showed cells attachment on implant surface. The ultimate failure load of the iron_SA_3_helix group was significantly higher than that of the polymer_SA group. The micro-CT analysis indicated the iron_SA_3_helix group showed a higher bone volume fraction (BV/TV) after surgery. Moreover, both iron SAs underwent degradation with time. Iron_SAs with triple-helical threads and a porous structure demonstrated better mechanical strength and high biocompatibility after short-term implantation. The combined advantages of the mechanical superiority of the iron metal and the possibility of absorption after implantation make the iron_SA a suitable candidate for further development.

Human Wharton's Jelly Mesenchymal Stem Cell-Mediated Sciatic Nerve Recovery Is Associated with the Upregulation of Regulatory T Cells.

The acceleration of peripheral nerve regeneration is crucial for functional nerve recovery. Our previous study demonstrated that human Wharton's jelly-derived mesenchymal stem cells (hWJ-MSC) promote sciatic nerve recovery and regeneration via the direct upregulation and release of neurotrophic factors. However, the immunomodulatory role of hWJ-MSC in sciatic nerve recovery remains unclear. The effects of hWJ-MSC on innate immunity, represented by macrophages, natural killer cells, and dendritic cells, as well as on adaptive immunity, represented by CD4+ T, CD8+ T, B, and regulatory T cells (Tregs), were examined using flow cytometry. Interestingly, a significantly increased level of Tregs was detected in blood, lymph nodes (LNs), and nerve-infiltrating cells on POD7, 15, 21, and 35. Anti-inflammatory cytokines, such as IL-4 and IL-10, were significantly upregulated in the LNs and nerves of hWJ-MSC-treated mice. Treg depletion neutralized the improved effects of hWJ-MSC on sciatic nerve recovery. In contrast, Treg administration promoted the functional recovery of five-toe spread and gait stance. hWJ-MSC also expressed high levels of the anti-inflammatory cytokines TGF-ß and IL-35. This study indicated that hWJ-MSC induce Treg development to modulate the balance between pro- and anti-inflammation at the injured sciatic nerve by secreting higher levels of anti-inflammatory cytokines.

Three-Dimensional Printed Porous Titanium Screw with Bioactive Surface Modification for Bone-Tendon Healing: A Rabbit Animal Model.

The interference screw fixation method is used to secure a graft in the tibial tunnel during anterior cruciate ligament reconstruction surgery. However, several complications have been reported, such as biodegradable screw breakage, inflammatory or foreign body reaction, tunnel enlargement, and delayed graft healing. Using additive manufacturing (AM) technology, we developed a titanium alloy (Ti6Al4V) interference screw with chemically calcium phosphate surface modification technology to improve bone integration in the tibial tunnel. After chemical and heat treatment, the titanium screw formed a dense apatite layer on the metal surface in simulated body fluid. Twenty-seven New Zealand white rabbits were randomly divided into control and additive manufactured (AMD) screw groups. The long digital extensor tendon was detached and translated into a tibial plateau tunnel (diameter: 2.0 mm) and transfixed with an interference screw while the paw was in dorsiflexion. Biomechanical analyses, histological analyses, and an imaging study were performed at 1, 3, and 6 months. The biomechanical test showed that the ultimate pull-out load failure was significantly higher in the AMD screw group in all tested periods. Micro-computed tomography analyses revealed early woven bone formation in the AMD screw group at 1 and 3 months. In conclusion, AMD screws with bioactive surface modification improved bone ingrowth and enhanced biomechanical performance in a rabbit model.

Dendritic cells treated with a prostaglandin I2 analog, iloprost, promote antigen-specific regulatory T cell differentiation in mice.

Iloprost, a stable prostaglandin I2 (PGI2) analog, can inhibit allergic inflammation in an ovalbumin (OVA)-induced asthma model via inhibition of airway dendritic cell (DC) function. However, the underlying mechanism of PGI2 signaling-mediated immunosuppression remains unclear. This study explored whether iloprost-treated DCs can suppress inflammation by promoting antigen-specific regulatory T cell (Treg) differentiation through PGI2-G-protein-coupled receptor (IP). We established an allergic lung inflammation model using a hydrogel biomaterial delivery system and observed that iloprost significantly suppressed OVA-induced Th2 lung inflammation and increased the frequency of OVA-specific Tregs in vivo. We further observed that iloprost-treated DCs displayed tolerogenic characteristics, including low inflammatory cytokine (IL-12, TNF-α, IL-6, IL-23) expression levels, high anti-inflammatory cytokine (IL-10) production, and a semimature phenotype. In addition, iloprost-treated DCs increased OVA-specific CD4+Foxp3+ T cell differentiation from naïve T cells in an IP-dependent pathway in vitro and in vivo. Blocking experiments showed that iloprost-treated DCs promoted Treg differentiation, at least in part, through programmed death ligand 1 (PD-L1), whereas iloprost-induced PD-L1 expression in DCs was through the IP receptor. Furthermore, iloprost treatment suppressed DC-mediated airway inflammation and increased the frequency of OVA-specific Tregs through PD-L1 in vivo. Taken together, these results show that PGI2-IP signaling mediated by iloprost in DCs may lead to immune tolerance, suggesting that the PGI2 analog has the potential to be applied therapeutically for tolerogenic DC immunotherapy in autoimmune diseases or allergic asthma.

One injection for one-week controlled release: In vitro and in vivo assessment of ultrasound-triggered drug release from injectable thermoresponsive biocompatible hydrogels.

Episodic release of bioactive compounds is often necessary for appropriate biological effects under specific physiological conditions. Here, we aimed to develop an injectable, biocompatible, and thermosensitive hydrogel system for ultrasound (US)-triggered drug release. An mPEG-PLGA-BOX block copolymer hydrogel was synthesized. The viscosity of 15 wt% hydrogel is 0.03 Pa*s at 25 °C (liquid form) and 34.37 Pa*s at 37 °C (gel form). Baseline and US-responsive in vitro release profile of a small molecule (doxorubicin) and that of a large molecule (FITC-dextran), from the hydrogel, was tested. A constant baseline release was observed in vitro for 7 d. When triggered by US (1 MHz, continuous, 0.4 W/cm2), the release rate increased by approximately 70 times. Without US, the release rate returned to baseline. Baseline and US-responsive in vivo release profile of doxorubicin was tested by subcutaneous injection in the back of mice and rats. Following injection into the subcutaneous layer, in vivo results also suggested that the hydrogels remained in situ and provided a steady release for at least 7 d; in the presence of the US-trigger, in vivo release from the hydrogel increased by approximately 10 times. Therefore, the mPEG-PLGA-BOX block copolymer hydrogel may serve as an injectable, biocompatible, and thermosensitive hydrogel system that is applicable for US-triggered drug release.

Topical Application of Human Wharton's Jelly Mesenchymal Stem Cells Accelerates Mouse Sciatic Nerve Recovery and is Associated with Upregulated Neurotrophic Factor Expression.

Peripheral nerve regeneration following injury is often slow and impaired, which results in weakened and denervated muscle with subsequent atrophy. Human Wharton's jelly mesenchymal stem cells (hWJ-MSC) have potential regenerative properties which, however, remain unknown in mouse nerve recovery. This study investigated the effect of the topical application of hWJ-MSC onto repairing transected sciatic nerves in a mouse model. Human adipocyte-derived stem cells (hADSC) were used as a positive control. The sciatic nerve of BALB/c mice was transected at a fixed point and repaired under the microscope using 10-0 sutures. hWJ-MSC and hADSC were applied to the site of repair and mice were followed up for 1 year. The hWJ-MSC group had significantly better functional recovery of five-toe spread and gait angles compared with the negative control and hADSC groups. hWJ-MSC improved sciatic nerve regeneration in a dose-dependent fashion. The hWJ-MSC group had a better quality of regenerated nerve with an increased number of myelinated axons throughout. hWJ-MSC appear to be safe in mice after 1 year of follow-up. hWJ-MSC also expressed higher levels of neurotrophic factor-3, brain-derived neurotrophic factor, and glial-derived neurotrophic factor than hADSC. hWJ-MSC may promote better nerve recovery than hADSC because of this upregulation of neurotrophic factors.

Augmentation of DMLS Biomimetic Dental Implants with Weight-Bearing Strut to Balance of Biologic and Mechanical Demands: From Bench to Animal.

A mismatch of elastic modulus values could result in undesirable bone resorption around the dental implant. The objective of this study was to optimize direct metal laser sintering (DMLS)-manufactured Ti6Al4V dental implants' design, minimize elastic mismatch, allow for maximal bone ingrowth, and improve long-term fixation of the implant. In this study, DMLS dental implants with different morphological characteristics were fabricated. Three-point bending, torsional, and stability tests were performed to compare the mechanical properties of different designs. Improvement of the weaker design was attempted by augmentation with a longitudinal 3D-printed strut. The osseointegrative properties were evaluated. The results showed that the increase in porosity decreased the mechanical properties, while augmentation with a longitudinal weight-bearing strut can improve mechanical strength. Maximal alkaline phosphatase gene expression of MG63 cells attained on 60% porosity Ti6Al4V discs. In vivo experiments showed good incorporation of bone into the porous scaffolds of the DMLS dental implant, resulting in a higher pull-out strength. In summary, we introduced a new design concept by augmenting the implant with a longitudinal weight-bearing strut to achieve the ideal combination of high strength and low elastic modulus; our results showed that there is a chance to reach the balance of both biologic and mechanical demands.

Treatment of osteoarthritis with collagen-based scaffold: A porcine animal model with xenograft mesenchymal stem cells.

OBJECTIVE: With the goal to explore a new approach to treat the early degenerative lesions of hyaline cartilage, we implanted in a porcine OA model a collagen-based scaffold containing chondroprogenitor cells derived from human bone marrow mesenchymal stem cells (hBM-MSCs). EXPERIMENTAL DESIGN: Porcine knee joints were subjected to anterior cruciate ligament (ACL) transection to surgically induce OA. After 4 months, the time necessary for the development of cartilage surface damage, animals were treated either with trephination bone plug wrapped with the chondroprogenic hBM-MSCs-embedded collagen scaffold or microfractures alone. Histological and histomorphometric evaluations were performed at 5 months after surgery. RESULTS: All animals subjected to ACL transection showed osteoarthritic changes including mild lateral femoral condyle or moderate medial femoral condyle ulcerations. After 14 days' chondrogenic induction, hBM-MSCs seeded onto the scaffold showed expression of chondroprogenitor markers such as SOX9 and COMP. At 5 months after the implantation, significant differences in the quality of the regenerated tissue were found between the hBM-MSCs-embedded scaffold group and the control group. Newly generated tissue was only observed at the site of implantation with the hBM-MSCs-embedded scaffolds. Furthermore, histological examination of the generated tissue revealed evidence of cartilage-like tissue with lacuna formation. In contrast, fibrous layers or fissures were formed on the surface of the control knee joint. CONCLUSIONS: This study shows that xenogenic hBM-MSC derived chondroprogenitor scaffolds can generate new cartilage tissue in porcine articular cartilage and have the potential as a useful treatment option for osteoarthritis.

Magnetic hyperthermia enhance the treatment efficacy of peri-implant osteomyelitis.

BACKGROUND: When bacteria colony persist within a biofilm, suitable drugs are not yet available for the eradication of biofilm-producing bacteria. The aim of this study is to study the effect of magnetic nano-particles-induced hyperthermia on destroying biofilm and promoting bactericidal effects of antibiotics in the treatment of osteomyelitis. METHODS: Sixty 12-weeks-old male Wistar rats were used. A metallic 18G needle was implanted into the bone marrow cavity of distal femur after the injection of Methicillin-sensitive Staphylococcus aureus (MSSA). All animals were divided into 5 different treatment modalities. The microbiological evaluation, scanning electron microscope examination, radiographic examination and then micro-CT evaluation of peri-implant bone resorption were analyzed. RESULTS: The pathomorphological characteristics of biofilm formation were completed after 40-days induction of osteomyelitis. The inserted implants can be heated upto 75 °C by magnetic heating without any significant thermal damage on the surrounding tissue. We also demonstrated that systemic administration of vancomycin [VC (i.m.)] could not eradicate the bacteria; but, local administration of vancomycin into the femoral canal and the presence of magnetic nanoparticles hyperthermia did enhance the eradication of bacteria in a biofilm-based colony. In these two groups, the percent bone volume (BV/TV: %) was significantly higher than that of the positive control. CONCLUSIONS: For the treatment of chronic osteomyelitis, we developed a new modality to improve antibiotic efficacy; the protection effect of biofilms on bacteria could be destroyed by magnetic nanoparticles-induced hyperthermia and therapeutic effect of systemic antibiotics could be enhanced.

A novel albumin-based tissue scaffold for autogenic tissue engineering applications.

Tissue scaffolds provide a framework for living tissue regeneration. However, traditional tissue scaffolds are exogenous, composed of metals, ceramics, polymers, and animal tissues, and have a defined biocompatibility and application. This study presents a new method for obtaining a tissue scaffold from blood albumin, the major protein in mammalian blood. Human, bovine, and porcine albumin was polymerised into albumin polymers by microbial transglutaminase and was then cast by freeze-drying-based moulding to form albumin tissue scaffolds. Scanning electron microscopy and material testing analyses revealed that the albumin tissue scaffold possesses an extremely porous structure, moderate mechanical strength, and resilience. Using a culture of human mesenchymal stem cells (MSCs) as a model, we showed that MSCs can be seeded and grown in the albumin tissue scaffold. Furthermore, the albumin tissue scaffold can support the long-term osteogenic differentiation of MSCs. These results show that the albumin tissue scaffold exhibits favourable material properties and good compatibility with cells. We propose that this novel tissue scaffold can satisfy essential needs in tissue engineering as a general-purpose substrate. The use of this scaffold could lead to the development of new methods of artificial fabrication of autogenic tissue substitutes.

Synthesis and interfacing of biocompatible iron oxide nanoparticles through the ferroxidase activity of Helicobacter Pylori ferritin.

Ferritin is an iron storage protein that is often used to coat metallic nanoparticles, such as iron oxide nanoparticles (IONPs). However, the synthesis and biocompatibility of ferritin-coated IONPs remain unclear. Therefore, this study reports the synthesis of a ferritin gene cloned and expressed from Helicobacter pylori (HPFn). The ferroxidase activity of the synthase HPFn was used for the de novo synthesis of HPFn-coated IONPs under mild conditions. Gel filtration chromatography and transmission electron microscopy analyses demonstrated that the core-shell structure of both the 5.0 nm IONP nanocore and the 12.4 nm HPFn shell were correctly assembled. The cellular uptake of mouse macrophage cells (RAW 264.7 cells) has shown that only a few HPFn-coated IONPs (3%) were taken up after 24 h of incubation. This study compares the biocompatibility of HPFn-coated IONPs, superparamagnetic iron oxide nanoparticles (SPIOs) and ferric salt (ferric ammonium citrate) in respect to cell growth inhibition, reactive oxygen species generation and pro-inflammatory cytokine TNF-α release. Assessment results showed that the responses elicited by HPFn-coated IONPs were similar to those elicited by SPIO treatment but milder than those elicited by ferric salt treatment. This accounts for the notion that ferritin-coated IONPs are biocompatible iron agents. These findings show that the ferroxidase activity of ferritin can be used to synthesize biocompatible IONPs. The favorable properties of HPFn-coated IONPs suggest that they can be used as a non-macrophage contrast agent through further surface conjugation.

Tracking T-cells in vivo with a new nano-sized MRI contrast agent.

Non-invasive in vivo tracking of T-cells by magnetic resonance imaging (MRI) can lead to a better understanding of many pathophysiological situations, including AIDS, cancer, diabetes, graft rejection. However, an efficient MRI contrast agent and a reliable technique to track non-phagocytic T-cells are needed. We report a novel superparamagnetic nano-sized iron-oxide particle, IOPC-NH2 series particles, coated with polyethylene glycol (PEG), with high transverse relaxivity (250 s(-1) mM(-1)), thus useful for MRI studies. IOPC-NH2 particles are the first reported magnetic particles that can label rat and human T-cells with over 90% efficiency, without using transfection agents, HIV-1 transactivator peptide, or electroporation. IOPC-NH2 particles do not cause any measurable effects on T-cell properties. Infiltration of IOPC-NH2-labeled T-cells can be detected in a rat model of heart-lung transplantation by in vivo MRI. IOPC-NH2 is potentially valuable contrast agents for labeling a variety of cells for basic and clinical cellular MRI studies, e.g., cellular therapy. FROM THE CLINICAL EDITOR: In this study, a novel PEG coated superparamagnetic nano-sized iron-oxide particle was investigated as a T-cell labeling agent for MRI studies. The reported particles can label T-cells with over 90% efficiency, without using transfection agents, HIV-1 transactivator peptide, or electroporation, therefore may enable more convenient preclinical call labeling studies.

A new nano-sized iron oxide particle with high sensitivity for cellular magnetic resonance imaging.

PURPOSE: In this study, we investigated the labeling efficiency and magnetic resonance imaging (MRI) signal sensitivity of a newly synthesized, nano-sized iron oxide particle (IOP) coated with polyethylene glycol (PEG), designed by Industrial Technology Research Institute (ITRI). PROCEDURES: Macrophages, bone-marrow-derived dendritic cells, and mesenchymal stem cells (MSCs) were isolated from rats and labeled by incubating with ITRI-IOP, along with three other iron oxide particles in different sizes and coatings as reference. These labeled cells were characterized with transmission electron microscopy (TEM), light and fluorescence microscopy, phantom MRI, and finally in vivo MRI and ex vivo magnetic resonance microscopy (MRM) of transplanted hearts in rats infused with labeled macrophages. RESULTS: The longitudinal (r (1)) and transverse (r (2)) relaxivities of ITRI-IOP are 22.71 and 319.2 s(-1) mM(-1), respectively. TEM and microscopic images indicate the uptake of multiple ITRI-IOP particles per cell for all cell types. ITRI-IOP provides sensitivity comparable or higher than the other three particles shown in phantom MRI. In vivo MRI and ex vivo MRM detect punctate spots of hypointensity in rejecting hearts, most likely caused by the accumulation of macrophages labeled by ITRI-IOP. CONCLUSION: ITRI-IOP, the nano-sized iron oxide particle, shows high efficiency in cell labeling, including both phagocytic and non-phagocytic cells. Furthermore, it provides excellent sensitivity in T(2)*-weighted MRI, and thus can serve as a promising contrast agent for in vivo cellular MRI.

Prokaryotic expression, refolding, and purification of functional human vascular endothelial growth factor isoform 165: purification procedures and refolding conditions revisited.

Human vascular endothelial growth factor isoform 165 (VEGF165) is the first known member belonging to the VEGF protein family that plays a critical role in new blood vessel formation in vivo. This study presents a new protocol with optimized conditions for rapidly producing untagged recombinant and biological active human VEGF165 (rhVEGF165) using Escherichia coli cells. Protein was isolated from inclusion bodies, purified by gel filtration and ion exchange chromatography, and subjected to protein refolding and renaturation. The biological activity of rhVEGF165 is comparable with VEFG from eukaryotic source according to human umbilical vein endothelial cells (HUVEC) proliferation assay. Therefore, the present procedures provide a fast and easy way to produce this therapeutic protein.