Development of finely tuned liposome nanoplatform for macrophage depletion

BACKGROUND

Immunotherapy with clodronate-encapsulated liposomes, which induce macrophage depletion, has been studied extensively. However, previously reported liposomal formulation-based drugs (Clodrosome® and m-Clodrosome®) are limited by their inconsistent size and therapeutic efficacy. Thus, we aimed to achieve consistent therapeutic effects by effectively depleting macrophages with uniform-sized liposomes.

RESULTS

We developed four types of click chemistry-based liposome nanoplatforms that were uniformly sized and encapsulated with clodronate, for effective macrophage depletion, followed by conjugation with Man-N3 and radiolabeling. Functionalization with Man-N3 improves the specific targeting of M2 macrophages, and radioisotope labeling enables in vivo imaging of the liposome nanoplatforms. The functionalized liposome nanoplatforms are stable under physiological conditions. The difference in the biodistribution of the four liposome nanoplatforms in vivo were recorded using positron emission tomography imaging. Among the four platforms, the clodronate-encapsulated mannosylated liposome effectively depleted M2 macrophages in the normal liver and tumor microenvironment ex vivo compared to that by Clodrosome® and m-Clodrosome®.

CONCLUSION

The newly-developed liposome nanoplatform, with finely tuned size control, high in vivo stability, and excellent ex vivo M2 macrophage targeting and depletion effects, is a promising macrophage-depleting agent.

Circulation Time-Optimized Albumin Nanoplatform for Quantitative Visualization of Lung Metastasis via Targeting of Macrophages

The development of molecular imaging probes to identify key cellular changes within lung metastases may lead to noninvasive detection of metastatic lesions in the lung. In this study, we constructed a macrophage-targeted clickable albumin nanoplatform (CAN) decorated with mannose as the targeting ligand using a click reaction to maintain the intrinsic properties of albumin in vivo. We also modified the number of mannose molecules on the CAN and found that mannosylated serum albumin (MSA) harboring six molecules of mannose displayed favorable pharmacokinetics that allowed high-contrast imaging of the lung, rendering it suitable for in vivo visualization of lung metastases. Due to the optimized control of functionalization and surface modification, MSA enhanced blood circulation time and active/passive targeting abilities and was specifically incorporated by mannose receptor (CD206)-expressing macrophages in the metastatic lung. Moreover, extensive in vivo imaging studies using single-photon emission computed tomography (SPECT)/CT and positron emission tomography (PET) revealed that blood circulation of time-optimized MSA can be used to discern metastatic lesions, with a strong correlation between its signal and metastatic burden in the lung.

Automation of the synthesis of highly concentrated 188Re-MAG3 for intracoronary radiation therapy

We have developed an efficient method and an automated synthetic system for the preparation of highly concentrated 188Re-MAG3. Routine production of 188Re-MAG3 for use in intracoronary radiation therapy was performed by compressed air driven semi-automated shielded system. 188Re-MAG3 was prepared with a commercial kit and reducing agents, purified and concentrated by C18 Sep-Pak cartridges to desired radioactivity and volume. Using this automated system, reproducible radiolabeling yields of 80-85% were obtained.

In vivo and in vitro demonstration of epithelial cell-induced myofibroblast differentiation of keratocytes and an inhibitory effect by amniotic membrane

PURPOSE

To examine the role of epithelial cells in inducing the differentiation of keratocytes into myofibroblasts and to determine whether this effect may be inhibited by amniotic membrane matrix.

METHODS

In vivo, a 9-mm diameter, partial-thickness corneal flap was created in 12 rabbit eyes (6 rabbits), which were equally subdivided into three groups. The first group was implanted with one layer of a 6-mm diameter human amniotic membrane, from which the epithelium had been removed by dispase. The second group received an implantation of dispase-treated amniotic membrane with cultured rabbit corneal epithelial cells. The third group received the same implantation as the second group except that the cultured corneal epithelial cells were sandwiched between two layers of membrane. All corneas were removed 2 weeks later and were subjected to Masson trichrome staining and immunofluorescence staining with monoclonal antibodies to alpha-smooth muscle (alpha-SM) actin for myofibroblasts and cytokeratins for epithelial cells. In vitro collagen gels impregnated with different types of human ocular surface fibroblasts were seeded with or without rabbit corneal epithelial cells before testing for gel contraction.

RESULTS

Positive staining of alpha-SM actin was noted only in keratocytes adjacent to corneal epithelial cells at the incision site and those grown on the basement membrane side of the amniotic membrane. Negative staining was noted when epithelial cells were removed by dispase or when cultured corneal epithelial cells were sandwiched between two layers of membrane. Gel contraction by fibroblasts was significantly promoted when epithelial cells were seeded on the gel. In the latter situation, positive staining of alpha-SM actin was noted in fibroblasts subjacent to epithelial cells but not in those impregnated in the gel.

CONCLUSION

Epithelial cells are capable of inducing the differentiation of adjacent fibroblasts into myofibroblasts; such an induction requires a close epithelial-mesenchymal contact. Amniotic membrane alone does not induce this effect and can help block such induction by epithelial cells.

Increased numbers of Langerhans cell and expression of HLA-Dr antigen in the giant papilla of patients with giant papillary conjunctivitis

A study of histopathologic changes, ultrastructure, and expression of the HLA-Dr antigen within the giant papillae of patients with giant papillary conjunctivitis was performed to determine whether cell-mediated immune response is related to this condition. Conjunctival giant papillae from ten patients with giant papillary conjunctivitis were examined by light and electron microscopy and by the indirect immunofluorescent staining method with HLA-Dr antibody. The infiltration of eosinophilic neutrophils and granules was most prominent, with the occasional infiltration of mast cells, as shown by light microscopy. The infiltration of activated fibroblasts and Langerhans cells was also observed. Cells expressing HLA-Dr antigen were also markedly increased, as shown by the immunofluorescent method. These findings suggest that delayed hypersensitivity may, along with the processes of antigen presentation by HLA-Dr-expressing (including Langerhans) cells, contribute to the pathogenesis of giant papillary conjunctivitis.

[Ratings of perceived exertion in a group of children while swimming at different temperatures]

The purpose of this study was to compare the Ratings of Perceived Exertion (RPE) in children while swimming at different temperatures. Five healthy male swimmers, aged 10 to 12, swam tethered using the breast stroke at 32 degrees C, 25 degrees C and 20 degrees C water temperature in a flume, and biked at 25 degrees C air temperature in contrast with swimming. In swimming, the resistance started at 1.0 kg and increased in 1.0 kg increments up to the point of exhaustion, and in bicycling, started at 0.5 kp with 60 rpm and increased in 0.5 kp increments, respectively. The subjects swam or biked for 5 min during each period, with a rest of 10 to 20 min until they had returned to their resting HR level. The last exercise intensity was for 5 min with the maximal weight the subjects could support. The last min of VO2 and 30 sec of HR were measured during each exercise period. The subjects gave their RPE assessment at the end of each exercise. The relationships between %VO2max and HR were linear with a high correlation coefficient (r = 0.995-0.998) in both water and air. However, the slope of the %VO2max-HR line tended to shift to the right in colder water. Increased VO2 of swimming in cold water was largely attributed to shivering. The RPE increased exponentially against %VO2max in both water and air and deviated more from linearity against HR. The RPE in 25 degrees C water was lowest at all submaximal swimming. At maximal swimming, however, the RPE in the four conditions were much the same. It seemed that the RPE responded differently from HR in varying water temperatures.

Contribution of differentiated ratings of perceived exertion to overall exertion in women while swimming

The purpose of this study was to identify, using multiple regression analysis, the contribution of differentiated ratings of perceived exertion to overall exertion (RPEO) in women while swimming. Ten female subjects swam at submaximal and maximal intensities and the variables measured included oxygen uptake (VO2), heart rate (fc), ventilation (VE), breathing frequency, tidal volume, blood lactate concentration ([la-]b), RPEO, and four differentiated RPE. These four differentiated RPE were cardiac frequency rating (RPEC), respiratory frequency rating (RPER), arm rating (RPE(arm)), and leg rating (RPE(leg)). These variables used the following equation based on VO2 - R = a + c.(S-b)n, where R was the response to increasing exercise intensity (S) and a, b, and c were constants. The exponents (n) of fc, VE and [la-]b were approximately 1.0, 2.0 and 3.3, respectively. The estimated exponents of RPEO, RPEC, RPER, RPE(arm) and RPE(leg) were approximately 2.4, 2.3, 2.2, 2.5 and 2.5, respectively. There was a highly significant relationship between the four differentiated RPE and their associated physiological responses. The results of this study showed that these interrelationships were clearly delineated. As the percentage maximal oxygen uptake (% VO2max) increased, the major contributing factor to RPEO changed. The RPEC was found to be the main contributing factor from 20% to 45% VO2max, but ceased to contribute beyond 50% VO2max. Above 45% VO2max, RPE(arm) was the major influence, and RPER was the secondary influence from 66% to 96% VO2max. The RPE(leg) was the secondary contributing factor only from 27% to 35% VO2max. It was concluded that differentiated RPE contribution was dependent upon the intensity of exercise in women while swimming.