Liposomes embedded within fibrin gels facilitate localized macrophage manipulations within nerve

Pan, Deng; Sayanagi, Junichi; Acevedo-Cintrón, Jesús A.; Schellhardt, Lauren; Snyder‐Warwick, Alison K.; Mackinnon, Susan E.; Wood, Matthew D.

doi:10.1016/j.jneumeth.2020.108981

Cited by 5 publications

(3 citation statements)

References 38 publications

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“…Clodronate is a small molecule that acts intracellularly to induce apoptosis. By encapsulating it in liposomes, its toxic activity can be restricted to phagocytic cells, predominantly macrophages [ 49 , 78 ], and clodronate liposomes have been used to deplete infiltrating macrophages in nerve injury models [ 79 – 81 ]. To restrict the activity of the clodronate further, clodronate or control liposomes were injected directly into the proximal CL site in a transection CL paradigm to target CL macrophages.…”

Section: Resultsmentioning

confidence: 99%

Neither injury induced macrophages within the nerve, nor the environment created by Wallerian degeneration is necessary for enhanced in vivo axon regeneration after peripheral nerve injury

Talsma,

Niemi,

Zigmond

2024

J Neuroinflammation

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Background Since the 1990s, evidence has accumulated that macrophages promote peripheral nerve regeneration and are required for enhancing regeneration in the conditioning lesion (CL) response. After a sciatic nerve injury, macrophages accumulate in the injury site, the nerve distal to that site, and the axotomized dorsal root ganglia (DRGs). In the peripheral nervous system, as in other tissues, the macrophage response is derived from both resident macrophages and recruited monocyte-derived macrophages (MDMs). Unresolved questions are: at which sites do macrophages enhance nerve regeneration, and is a particular population needed. Methods Ccr2 knock-out (KO) and Ccr2gfp/gfp knock-in/KO mice were used to prevent MDM recruitment. Using these strains in a sciatic CL paradigm, we examined the necessity of MDMs and residents for CL-enhanced regeneration in vivo and characterized injury-induced nerve inflammation. CL paradigm variants, including the addition of pharmacological macrophage depletion methods, tested the role of various macrophage populations in initiating or sustaining the CL response. In vivo regeneration, measured from bilateral proximal test lesions (TLs) after 2 d, and macrophages were quantified by immunofluorescent staining. Results Peripheral CL-enhanced regeneration was equivalent between crush and transection CLs and was sustained for 28 days in both Ccr2 KO and WT mice despite MDM depletion. Similarly, the central CL response measured in dorsal roots was unchanged in Ccr2 KO mice. Macrophages at both the TL and CL, but not between them, stained for the pro-regenerative marker, arginase 1. TL macrophages were primarily CCR2-dependent MDMs and nearly absent in Ccr2 KO and Ccr2gfp/gfp KO mice. However, there were only slightly fewer Arg1+ macrophages in CCR2 null CLs than controls due to resident macrophage compensation. Zymosan injection into an intact WT sciatic nerve recruited Arg1+ macrophages but did not enhance regeneration. Finally, clodronate injection into Ccr2gfp KO CLs dramatically reduced CL macrophages. Combined with the Ccr2gfp KO background, depleting MDMs and TL macrophages, and a transection CL, physically removing the distal nerve environment, nearly all macrophages in the nerve were removed, yet CL-enhanced regeneration was not impaired. Conclusions Macrophages in the sciatic nerve are neither necessary nor sufficient to produce a CL response.

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Section: Resultsmentioning

confidence: 99%

Neither injury induced macrophages within the nerve, nor the environment created by Wallerian degeneration is necessary for enhanced in vivo axon regeneration after peripheral nerve injury

Talsma,

Niemi,

Zigmond

2024

J Neuroinflammation

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“…The next step was to evaluate the cellular uptake of the liposomes. For this purpose, we labeled liposomes with Nile Red, which is commonly used for bioimaging studies [ 53 , 54 , 55 ]. Confocal microscopy observation was performed using fluorescence signals from two fluorophores: one from cell nuclei stained with DAPI, the second from DiL encapsulated in liposomes, with the addition of transmitted light as well.…”

Section: Resultsmentioning

confidence: 99%

Novel Liposomal Formulation of Baicalein for the Treatment of Pancreatic Ductal Adenocarcinoma: Design, Characterization, and Evaluation

et al. 2023

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Pancreatic cancer (PC) is one of the deadliest cancers so there is an urgent need to develop new drugs and therapies to treat it. Liposome-based formulations of naturally-derived bioactive compounds are promising anticancer candidates due to their potential for passive accumulation in tumor tissues, protection against payload degradation, and prevention of non-specific toxicity. We chose the naturally-derived flavonoid baicalein (BAI) due to its promising effect against pancreatic ductal adenocarcinoma (PDAC) and encapsulated it into a liposomal bilayer using the passive loading method, with an almost 90% efficiency. We performed a morphological and stability analysis of the obtained BAI liposomal formulation and evaluated its activity on two-dimensional and three-dimensional pancreatic cell models. As the result, we obtained a stable BAI-encapsulated liposomal suspension with a size of 100.9 nm ± 2.7 and homogeneity PDI = 0.124 ± 0.02, suitable for intravenous administration. Furthermore, this formulation showed high cytotoxic activity towards AsPC-1 and BxPC-3 PDAC cell lines (IC50 values ranging from 21 ± 3.6 µM to 27.6 ± 4.1 µM), with limited toxicity towards normal NHDF cells and a lack of hemolytic activity. Based on these results, this new BAI liposomal formulation is an excellent candidate for potential anti-PDAC therapy.

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“…The right sciatic nerve was exposed and transected. The proximal and distal transected nerves were secured inside a silicone tube for a 3-mm gap between the nerve ends, with 10 μL of the fibrin hydrogel (similar to previous methods 12 ) containing 100 000 BMDM/gel for the "fibrin+Mφ" group, whereas media alone was used in the "fibrin" hydrogel group. The animals were recovered and returned to a central facility.…”

Section: Nerve Injury Repair Model and Designmentioning

confidence: 99%

A feasibility study transplanting macrophages to a segmental nerve injury

Pan,

Schofield,

Schellhardt

et al. 2023

Muscle and Nerve

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Introduction/AimsPromoting regeneration after segmental nerve injury repair is a challenge, but improving angiogenesis could be beneficial. Macrophages facilitate regeneration after injury by promoting angiogenesis. Our aim in this study was to evaluate the feasibility and effects of transplanting exogenous macrophages to a segmental nerve injury.MethodsBone marrow–derived cells were harvested from donor mice and differentiated to macrophages (BMDM), then suspended within fibrin hydrogels to facilitate BMDM transplantation. BMDM survival was characterized in vitro. The effect of this BMDM fibrin hydrogel construct at a nerve injury site was assessed using a mouse sciatic nerve gap injury. Mice were equally distributed to “fibrin+Mφ” (fibrin hydrogels containing culture medium and BMDM) or “fibrin” hydrogel control (fibrin hydrogels containing culture medium alone) groups. Flow cytometry (n = 3/group/endpoint) and immunohistochemical analysis (n = 5/group/endpoint) of the nerve gap region were performed at days 3, 5, and 7 after repair.ResultsIncorporating macrophage colony‐stimulating factor (M‐CSF) improved BMDM survival and expansion. Transplanted BMDM survived for at least 7 days in a nerve gap (~40% retained at day 3 and ~15% retained at day 7). From transplantation, macrophage quantities within the nerve gap were elevated when comparing fibrin+Mφ with fibrin control (~25% vs. 3% at day 3 and ~14% vs. 6% at day 7). Endothelial cells increased by about fivefold within the nerve gap, and axonal extension into the nerve gap increased almost twofold for fibrin+Mφ compared with fibrin control.DiscussionBMDM suspended within fibrin hydrogels at a nerve gap do not impair regeneration.

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Liposomes embedded within fibrin gels facilitate localized macrophage manipulations within nerve

Cited by 5 publications

References 38 publications

Neither injury induced macrophages within the nerve, nor the environment created by Wallerian degeneration is necessary for enhanced in vivo axon regeneration after peripheral nerve injury

Neither injury induced macrophages within the nerve, nor the environment created by Wallerian degeneration is necessary for enhanced in vivo axon regeneration after peripheral nerve injury

Novel Liposomal Formulation of Baicalein for the Treatment of Pancreatic Ductal Adenocarcinoma: Design, Characterization, and Evaluation

A feasibility study transplanting macrophages to a segmental nerve injury

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