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In situ modulation of dendritic cells by injectable thermosensitive hydrogels for cancer vaccines in mice.

Liu Y, Xiao L, Joo KI, Hu B, Fang J, Wang P - Biomacromolecules (2014)

Bottom Line: Attempts to develop cell-based cancer vaccines have shown limited efficacy, partly because transplanted dendritic cells (DCs) do not survive long enough to reach the lymph nodes.We demonstrate that GM-CSF-releasing mPEG-PLGA hydrogels successfully recruit and house DCs and macrophages, allowing the subsequent introduction of antigens by vectors to activate the resident cells, thus, initiating antigen presentation and triggering immune response.This injectable thermosensitive hydrogel shows great promise as an adjuvant for cancer vaccines, potentially providing a new approach for cell therapies through in situ modulation of cells.

View Article: PubMed Central - PubMed

Affiliation: Mork Family Department of Chemical Engineering and Materials Science, ‡Department of Biomedical Engineering, and §Department of Pharmacology and Pharmaceutical Sciences, University of Southern California , Los Angeles, California 90089, United States.

ABSTRACT
Attempts to develop cell-based cancer vaccines have shown limited efficacy, partly because transplanted dendritic cells (DCs) do not survive long enough to reach the lymph nodes. The development of biomaterials capable of modulating DCs in situ to enhance antigen uptake and presentation has emerged as a novel method toward developing more efficient cancer vaccines. Here, we propose a two-step hybrid strategy to produce a more robust cell-based cancer vaccine in situ. First, a significant number of DCs are recruited to an injectable thermosensitive mPEG-PLGA hydrogel through sustained release of chemoattractants, in particular, granulocyte-macrophage colony-stimulating factor (GM-CSF). Then, these resident DCs can be loaded with cancer antigens through the use of viral or nonviral vectors. We demonstrate that GM-CSF-releasing mPEG-PLGA hydrogels successfully recruit and house DCs and macrophages, allowing the subsequent introduction of antigens by vectors to activate the resident cells, thus, initiating antigen presentation and triggering immune response. Moreover, this two-step hybrid strategy generates a high level of tumor-specific immunity, as demonstrated in both prophylactic and therapeutic models of murine melanoma. This injectable thermosensitive hydrogel shows great promise as an adjuvant for cancer vaccines, potentially providing a new approach for cell therapies through in situ modulation of cells.

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In vitro recruitment of dendritic cells and macrophages by GM-CSF-loadedhydrogels. (A) mPEG–PLGA copolymer formulations are an injectablesolution at 4 °C, but turn to gel after incubation at 37 °Cfor 5 min. (B) The release profiles of FITC-labeled GM-CSF from hydrogelformulations (15, 20, and 25 wt %; n = 3). (C) Invitro chemotaxis using a transwell migration assay. Chemotaxis ofBMDCs and BMDMs in response to hydrogels encapsulating various dosesof GM-CSF was determined by counting the number of BMDCs and BMDMsmigrating to the lower compartment of transwell (n = 3).
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fig1: In vitro recruitment of dendritic cells and macrophages by GM-CSF-loadedhydrogels. (A) mPEG–PLGA copolymer formulations are an injectablesolution at 4 °C, but turn to gel after incubation at 37 °Cfor 5 min. (B) The release profiles of FITC-labeled GM-CSF from hydrogelformulations (15, 20, and 25 wt %; n = 3). (C) Invitro chemotaxis using a transwell migration assay. Chemotaxis ofBMDCs and BMDMs in response to hydrogels encapsulating various dosesof GM-CSF was determined by counting the number of BMDCs and BMDMsmigrating to the lower compartment of transwell (n = 3).

Mentions: As illustrated inScheme 1, our goal wasto develop an injectable biomaterial with high cytokine encapsulationefficiency to attract DCs to a defined injection site where antigenscould be introduced, thereby enhancing antigen uptake to DCs. To accomplishthis, we adapted a previously reported procedure19 to generate a thermosensitive hydrogel, consisting of adiblock copolymer of mPEG (polyethylene glycol) and FDA-approved PLGA(lactic acid and glycolic acid) polymer. This polymeric formulationis in the solution phase at 4 °C and shows a fast sol–geltransition at 37 °C, within 5 min (Figure 1A). This simple formulation procedure allows almost 100% encapsulationefficiency of cytokine granulocyte-macrophage colony-stimulating factor(GM-CSF) (Figure 1B). Additionally, linearlysustained release profiles of GM-CSF can be achieved in 15, 20, and25 wt % aqueous solutions of the mPEG–PLGA diblock copolymer,as shown in Figure 1B. To examine whether thehydrogel-released GM-CSF remained sufficiently functional to recruitDCs and macrophages toward the hydrogel area, an in vitro transwellcell migration assay was developed. Briefly, hydrogels encapsulatingvarious amounts of GM-CSF were placed in the lower compartment ofthe transwell, while the bone marrow-derived dendritic cells (BMDCs)and bone marrow-derived macrophages (BMDMs) were seeded in the uppercompartment. The chemotaxis of BMDCs and BMDMs in response to GM-CSFgradient was determined by counting the cells that migrated to thelower compartment. As shown in Figure 1C,D,significantly more migrating BMDCs and BMDMs were found for hydrogelscontaining 5 μg of GM-CSF compared to lower doses of GM-CSF(p < 0.05), indicating that the GM-CSF releasedfrom hydrogel enhanced DC and macrophage recruitment in a dose-dependentmanner.


In situ modulation of dendritic cells by injectable thermosensitive hydrogels for cancer vaccines in mice.

Liu Y, Xiao L, Joo KI, Hu B, Fang J, Wang P - Biomacromolecules (2014)

In vitro recruitment of dendritic cells and macrophages by GM-CSF-loadedhydrogels. (A) mPEG–PLGA copolymer formulations are an injectablesolution at 4 °C, but turn to gel after incubation at 37 °Cfor 5 min. (B) The release profiles of FITC-labeled GM-CSF from hydrogelformulations (15, 20, and 25 wt %; n = 3). (C) Invitro chemotaxis using a transwell migration assay. Chemotaxis ofBMDCs and BMDMs in response to hydrogels encapsulating various dosesof GM-CSF was determined by counting the number of BMDCs and BMDMsmigrating to the lower compartment of transwell (n = 3).
© Copyright Policy - editor-choice
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4195289&req=5

fig1: In vitro recruitment of dendritic cells and macrophages by GM-CSF-loadedhydrogels. (A) mPEG–PLGA copolymer formulations are an injectablesolution at 4 °C, but turn to gel after incubation at 37 °Cfor 5 min. (B) The release profiles of FITC-labeled GM-CSF from hydrogelformulations (15, 20, and 25 wt %; n = 3). (C) Invitro chemotaxis using a transwell migration assay. Chemotaxis ofBMDCs and BMDMs in response to hydrogels encapsulating various dosesof GM-CSF was determined by counting the number of BMDCs and BMDMsmigrating to the lower compartment of transwell (n = 3).
Mentions: As illustrated inScheme 1, our goal wasto develop an injectable biomaterial with high cytokine encapsulationefficiency to attract DCs to a defined injection site where antigenscould be introduced, thereby enhancing antigen uptake to DCs. To accomplishthis, we adapted a previously reported procedure19 to generate a thermosensitive hydrogel, consisting of adiblock copolymer of mPEG (polyethylene glycol) and FDA-approved PLGA(lactic acid and glycolic acid) polymer. This polymeric formulationis in the solution phase at 4 °C and shows a fast sol–geltransition at 37 °C, within 5 min (Figure 1A). This simple formulation procedure allows almost 100% encapsulationefficiency of cytokine granulocyte-macrophage colony-stimulating factor(GM-CSF) (Figure 1B). Additionally, linearlysustained release profiles of GM-CSF can be achieved in 15, 20, and25 wt % aqueous solutions of the mPEG–PLGA diblock copolymer,as shown in Figure 1B. To examine whether thehydrogel-released GM-CSF remained sufficiently functional to recruitDCs and macrophages toward the hydrogel area, an in vitro transwellcell migration assay was developed. Briefly, hydrogels encapsulatingvarious amounts of GM-CSF were placed in the lower compartment ofthe transwell, while the bone marrow-derived dendritic cells (BMDCs)and bone marrow-derived macrophages (BMDMs) were seeded in the uppercompartment. The chemotaxis of BMDCs and BMDMs in response to GM-CSFgradient was determined by counting the cells that migrated to thelower compartment. As shown in Figure 1C,D,significantly more migrating BMDCs and BMDMs were found for hydrogelscontaining 5 μg of GM-CSF compared to lower doses of GM-CSF(p < 0.05), indicating that the GM-CSF releasedfrom hydrogel enhanced DC and macrophage recruitment in a dose-dependentmanner.

Bottom Line: Attempts to develop cell-based cancer vaccines have shown limited efficacy, partly because transplanted dendritic cells (DCs) do not survive long enough to reach the lymph nodes.We demonstrate that GM-CSF-releasing mPEG-PLGA hydrogels successfully recruit and house DCs and macrophages, allowing the subsequent introduction of antigens by vectors to activate the resident cells, thus, initiating antigen presentation and triggering immune response.This injectable thermosensitive hydrogel shows great promise as an adjuvant for cancer vaccines, potentially providing a new approach for cell therapies through in situ modulation of cells.

View Article: PubMed Central - PubMed

Affiliation: Mork Family Department of Chemical Engineering and Materials Science, ‡Department of Biomedical Engineering, and §Department of Pharmacology and Pharmaceutical Sciences, University of Southern California , Los Angeles, California 90089, United States.

ABSTRACT
Attempts to develop cell-based cancer vaccines have shown limited efficacy, partly because transplanted dendritic cells (DCs) do not survive long enough to reach the lymph nodes. The development of biomaterials capable of modulating DCs in situ to enhance antigen uptake and presentation has emerged as a novel method toward developing more efficient cancer vaccines. Here, we propose a two-step hybrid strategy to produce a more robust cell-based cancer vaccine in situ. First, a significant number of DCs are recruited to an injectable thermosensitive mPEG-PLGA hydrogel through sustained release of chemoattractants, in particular, granulocyte-macrophage colony-stimulating factor (GM-CSF). Then, these resident DCs can be loaded with cancer antigens through the use of viral or nonviral vectors. We demonstrate that GM-CSF-releasing mPEG-PLGA hydrogels successfully recruit and house DCs and macrophages, allowing the subsequent introduction of antigens by vectors to activate the resident cells, thus, initiating antigen presentation and triggering immune response. Moreover, this two-step hybrid strategy generates a high level of tumor-specific immunity, as demonstrated in both prophylactic and therapeutic models of murine melanoma. This injectable thermosensitive hydrogel shows great promise as an adjuvant for cancer vaccines, potentially providing a new approach for cell therapies through in situ modulation of cells.

Show MeSH
Related in: MedlinePlus