Lymphatic Reconnection and Restoration of Lymphatic Flow by Nonvascularized Lymph Node Transplantation: Real-Time Fluorescence Imaging Using Indocyanine Green and Fluorescein Isothiocyanate–Dextran

Synergistic anti-tumor effects of oncolytic virus and anti-programmed cell death protein 1 antibody combination therapy: For suppression of lymph node and distant metastasis in a murine melanoma model

It is believed that oncolytic viruses (OVs) exert both direct anti-tumor effects by intratumoral injection as well as indirect anti-tumor effects by activating systemic immunity. In phase III clinical trials, OV and anti-programmed cell death-1 (aPD-1) antibody combination therapy showed no significant differences in overall survival and progression-free survival in patients with unresectable advanced melanoma. In the study, OVs can exert only indirect anti-tumor effects in non-injected, systemic lesions. If the tumor is at a stage where both direct and indirect anti-tumor effects of OVs can be expected, OVs may further enhance the therapeutic effect, in addition to the clinically expected therapeutic effect. Therefore, we investigated whether canerpaturev (C-REV) and aPD-1 antibody combination therapy suppresses tumor progression in a murine melanoma model. Our findings showed that the C-REV and aPD-1 antibody combination therapy suppressed tumor progression in a murine melanoma model. The combination therapy stimulated systemic immunity in lymphoid tissues by activating helper T cells and B cells to enhance adaptive and humoral immunity, as well as by increasing effector/memory T cell fractions. Synergistically enhanced systemic anti-tumor effects suppressed lymph node and lung metastases. These findings suggest that direct anti-tumor effects by infecting and destroying cancer cells from within and indirect anti-tumor effects enhanced by the combination therapy worked simultaneously to suppress tumor progression. Our results may provide evidence to support the usefulness of OV and aPD-1 antibody combination therapy as a neoadjuvant therapy in the surgical treatment of melanoma.

Improved lymphangiogenesis around vascularized lymph node flaps by periodic injection of hyaluronidase in a rodent model

Vascularized lymph node transfer (VLNT) is an advanced surgical approach for secondary lymphedema (SLE) treatment, but tissue fibrosis around the lymph node flap (VLNF) inhibiting lymphangiogenesis is the biggest challenge undermining its therapeutic efficacy. This study explored the effects of periodic hyaluronidase (HLD) injection in reducing fibrosis and promoting lymphangiogenesis in 52 Sprague-Dawley rats with a VLNF over 13 weeks. The results demonstrated that HLD administration significantly enhanced swelling reduction, lymphatic drainage efficiency, and lymphatic vessel regeneration, with up to a 26% decrease in tissue fibrosis around the VLNF. These findings suggest that combining VLNT with periodic injections of HLD could substantially improve SLE treatment outcomes in clinical settings. It offers a promising direction for future therapeutic strategies and drug development aimed at increasing the efficacy of surgical treatment for SLE patients.

Lymphangiogenesis after nonvascularized lymph node transplantation: Lymphangiographic findings in mice and minipigs

The establishment of new connections after NVLNT (non-vascularized lymph node transplantation) is still poorly understood. The purpose of this study was to investigate lymphatic connections after NVLNT using lymphangiography. In a mice model, 40 mice were allocated to undergo NVLNT or sham surgery. On day 21 after NVLNT, the lymphatic vessels were observed on near-infrared fluorescence imaging with indocyanine green. In a minipig model, 12 minipigs underwent NVLNT. On day 14 after NVLNT, the transplanted lymph node and donor site were checked by ultrasound, and minipigs with viable transplanted LNs were allocated to lipiodol lymphangiography or MR lymphangiography groups. Transplanted LN engraftment was examined with immunohistochemical staining. After NVLNT in mice, the signal intensities in the popliteal region at 3 minutes and 5 minutes were higher in the transplanted side than the control side (21.3 ± 8.1 vs. 11.0 ± 4.6 at 3 minutes, 26.7 ± 6.8 vs. 19.7 ± 5.9 at 5 minutes), while in the sham group, there were no significant differences between sides. In minipigs, lipiodol lymphangiography (n = 5) showed Lipiodol accumulation in transplanted LNs with innumerable newly formed lymphatic vessels and lymphovenous shunts. MR lymphangiography (n = 5) showed higher enhancement on the transplanted side compared to the control side. Histology showed successful engraftment of transplanted LNs in 16 out of 20 (80%) mice and 9 out of 12 (75%) minipigs. Omnidirectional lymphangiogenesis forming a dense lymphatic network and spontaneous formation of lymphovenous shunts were shown after NVLNT.

Use of fluorescence imaging during lymphatic surgery: A Delphi survey of experts worldwide

BACKGROUND

Fluorescence imaging with indocyanine green is increasingly used during lymphedema patient management. However, to date, no guidelines exist on when it should and should not be used or how it should be performed. Our objective was to have an international panel of experts identify areas of consensus and nonconsensus in current attitudes and practices in fluorescence imaging with indocyanine green use during lymphedema surgery patient management.

METHODS

A 2-round Delphi study was conducted involving 18 experts in the use of fluorescence imaging during lymphatic surgery, all asked to vote on 49 statements on patient preparation and contraindications (n = 7 statements), indocyanine green dosing and administration (n = 10), fluorescence imaging uses and potential advantages (n = 16), and potential disadvantages and training needs (n = 16).

RESULTS

Consensus ultimately was reached on 40/49 statements, including consistent consensus regarding the value of fluorescence imaging with indocyanine green in almost all facets of lymphedema patient management, including early detection, assessing disease extent, preoperative work-up, surgical planning, intraoperative guidance, monitoring short- and longer-term outcomes, quality control, and resident training. All experts felt it was very safe, while 94% felt it should be part of routine care and that indocyanine green was superior to colored dyes and ultrasound. Nonetheless, there also was consensus that limited high-quality evidence remains a barrier to its widespread use and that patients should still be provided with specific information and asked to sign specific consent for both fluorescence imaging and indocyanine green.

CONCLUSION

Fluorescence imaging with or without indocyanine green appears to have several roles in lymphedema prevention, diagnosis, assessment, and treatment.

Restoration of lymph flow by flap transfer can prevent severe lower extremity lymphedema after inguino-pelvic lymphadenectomy

PURPOSE

Severe lymphedema is difficult to treat because of the associated extensive scar formation. Therefore, preventing scar formation might alleviate the severity of lymphedema following lymphadenectomy. In this study, we evaluated the usefulness of flap transfer, performed immediately after lymphadenectomy, for preventing scar formation.

METHODS

Twenty-three patients with subcutaneous malignancy in a lower extremity, who underwent inguino-pelvic lymphadenectomy, were divided into groups based on whether flap transfer was performed. The severity of lymphedema was categorized according to the ratio of the circumference of the affected extremity to that of the unaffected extremity, as mild (< 20% increase in volume), moderate (20-40%), or severe (> 40%).

RESULTS

In the 18 patients who underwent lymphadenectomy without flap transfer, lymphedema was classified as mild in 7, moderate in 7, and severe in 4. In the five patients who underwent lymphadenectomy with flap transfer, lymphedema was classified as mild in 4 and moderate in 1. This difference between the groups did not reach significance.

CONCLUSIONS

The findings of this study suggest that flap transfer may help prevent scar formation and contribute to the restoration of lymph flow after lymphadenectomy.

Hormone Therapy: A Potential Risk Factor Affecting Survival and Functional Restoration of Transplanted Lymph Nodes

Background: Transplantation of lymph nodes (LNs) is an increasingly popular option for treating lymphedema. Increasing evidence indicates an intrinsic correlation between estrogen signaling and the lymphatic system. We explored the effects of 17β estradiol and antiestrogen treatment (tamoxifen) on the survival and functional restoration of transplanted popliteal lymph nodes (PLNs).

Methods: A total of forty-eight ovariectomized mice were divided into three groups of 16: OVX + E2 (treated with 17β-estradiol), OVX + TMX (treated with tamoxifen), and OVX (control; treated with olive oil as a solvent). After 2 weeks, PLNs were transplanted. Then, reconnections of lymphatic vessels were observed, and the morphology and survival of transplanted PLNs were evaluated 4 weeks after transplantation. T cells, B cells, lymphatic vessels, and high endothelial venules (HEVs) were subjected to immunofluorescence staining or immunohistochemical staining and quantified.

Results: The percentage of lymphatic reconnections was 93.75% in the OVX + E2 group, 68.75% in the OVX + TMX group, and 75% in the OVX group. Surviving PLNs were observed in 16 of 16 in the OVX + E2 group, seven of 16 in the OVX + TMX group, and 13 of 16 in the OVX group. The mean size of PLNs in the largest cross section of the OVX + TMX group was significantly lower than that in the other groups. The distributions of B cells and T cells in surviving PLNs were similar to those in normal LNs. The ratio of dilated HEVs/total HEVs and density of lymphatic vessels in the OVX + E2 group were the highest among the three groups, whereas the lowest ratio and density were observed in the OVX + TMX group.

Conclusion: Tamoxifen treatment might lead to cellular loss of transplanted LNs and interfere with the structural reconstruction and functional restoration, thereby inhibiting the survival of transplanted PLNs. Estrogen treatment facilitated the maintenance and regeneration of functional HEVs as well as lymphangiogenesis.

Combined lymph node transfer and suction-assisted lipectomy in lymphedema treatment: A prospective study

BACKGROUND

Recent studies have analyzed the combination of suction-assisted lipectomy (SAL) and vascularized lymph node transfer (VLNT) in lymphedema treatment, reporting positive outcomes. However, it is difficult to draw conclusions due to the heterogeneity of the studies. Aim of this prospective study is to evaluate the effectiveness of the combination of VLNT and SAL in lymphedema treatment.

PATIENTS AND METHODS

Between January 2016 and May 2019, 94 patients with upper or lower limb stage IIb-III lymphedema were enrolled and treated with the gastroepiploic VLNT followed by SAL. Patients were prospectively evaluated through circumference measurement and clinical examination, including number of episodes of cellulitis.

RESULTS

Among patients enrolled in the study 83 were affected by lower limb lymphedema (LLL) and 11 were affected by upper limb lymphedema (ULL). Average follow-up was 3 ± 0.8 years. In the LLL group, the mean circumference reduction rates (CRR) were 60.4, 56.9, 29.6, and 55.4% above and below the knee, above the ankle, and at the foot level, respectively. A statistically significant difference was noted at all the levels (p < .05), but above the ankle (p = .059). Regarding the ULL group, the mean CRR were 80.7, 60.7, 65.0 and 49.6% above and below the elbow, at wrist and at mid-hand, respectively. CRR were reported at all the levels but no statistical difference was noted. The number of episodes of cellulitis dropped significantly (p < .05).

CONCLUSION

This study supports the use of VLNT+SAL in lymphedema grades IIb-III, with important implications for the clinical practice.

A prospective study on combined lymphedema surgery: Gastroepiploic vascularized lymph nodes transfer and lymphaticovenous anastomosis followed by suction lipectomy

BACKGROUND

There is no consensus on the appropriate treatment of lymphedema. Proposed techniques include lymphaticovenous anastomosis (LVA), vascularized lymph nodes transfer (VLNT), and suction lipectomy (SL). The benefit of combined procedures has also been postulated. In this prospective study, a combined protocol is proposed as an alternative to single-procedure strategies.

METHODS

Between January 2016 and October 2018, we enrolled patients with secondary lymphedema of lower limbs, stage II-III according to the International Society of Lymphology, progressive swelling and skin tonicity >60. Thirty-seven consecutive patients were dichotomized into group I, undergoing VLNT, and group II undergoing VLNT and LVA. Gastroepiploic lymphnode flap was harvested through laparoscopy, and in the same operation, LVAs were performed in group II on the basis of indocyanine green lymphography and patent blue findings. Two weeks later, SL was performed in all the patients. Patients were prospectively evaluated through clinical examination, circumference measurement, and skin tonicity.

RESULTS

The average follow-up was 2 ± 0.8 years. The first consecutive 21 patients were treated with VLNT followed by SL. The next 16 patients underwent combined VLNT and LVA, followed by SL. A mean of 2.4 LVAs were performed. A significant difference in the postoperative circumference measurements was found overall (p < .05): 52.6 ± 18.9 above the knee, 42.9 ± 25 below the knee, 36.2 ± 37 at foot. The postoperative tonicity dropped by 12.7 ± 6.3% (p < .05). The episodes of cellulitis significantly decreased to 0.1 ± 0.3 (p < .05).

CONCLUSIONS

LVA, VLNT, and SL can be integrated together in a combined approach, in synergy to enhance the outcomes.

Changes in high endothelial venules in lymph nodes after vascularized and nonvascularized lymph node transfer in a murine autograft model

BACKGROUND AND OBJECTIVES

Vascularized lymph node transfer (LNT) is gaining popularity in the treatment of lymphedema. However, it is unclear whether the vascularization of transferred lymph nodes (LNs) contributes to functional improvement. High endothelial venules (HEVs) are specialized vessels that allow lymphocytes to enter LNs. In this study, we compared the numbers of HEVs and lymphocytes in LNs after vascularized and nonvascularized LNT.

METHODS

Fifty mice were divided into three groups (group 1, pedicled vascularized LNT; group 2, pedicled nonvascularized LNT; group 3, free nonvascularized LNT). Afferent lymphatic reconnection was confirmed by patent blue staining. The transferred LNs were harvested 4 weeks after surgery. HEVs, B-cells, and T-cells were subjected to immunohistochemical staining and quantified.

RESULTS

Afferent lymphatic reconnection was observed in 13 of 20 transferred LNs in group 1, 11 of 15 in group 2, and 7 of 15 in group 3. The ratio of dilated/total HEVs in transferred LNs with afferent lymphatic reconnection was significantly higher in group 1 than in groups 2 and 3. No significant differences in numbers of B-cells and T-cells were found in the transferred LNs.

CONCLUSIONS

We found that more functional HEVs were preserved in cases with successful afferent lymphatic reconnection after vascularized LNT than after nonvascularized LNT.

Feasibility of pedicled vascularized inguinal lymph node transfer in a mouse model: A preliminary study

PURPOSE

Vascularized lymph node transfer is becoming more common in the treatment of lymphedema, but suitable small animal models for research are lacking. Here, we evaluated the feasibility of pedicled vascularized inguinal lymph node transfer in mice.

METHODS

Twenty-five mice were used in the study. An inguinal lymph node-bearing flap with a vascular pedicle containing the superficial caudal epigastric vessels was transferred into the ipsilateral popliteal fossa after excision of the popliteal lymph node. Indocyanine green (ICG) angiography was used to confirm vascularity of the flap. ICG lymphography was performed to evaluate lymphatic flow at 3 and 4 weeks postoperatively. Patent blue dye was injected into the ipsilateral hind paw to observe staining of the transferred lymph node at 4 weeks postoperatively. All transferred lymph nodes were then harvested and histologically evaluated by hematoxylin and eosin staining.

RESULTS

In 16 of the 25 mice, ICG lymphography showed reconnection between the transferred lymph node and the afferent lymphatic vessels, as confirmed by patent blue staining. Histologically, these transferred lymph nodes with afferent lymphatic reconnection significantly regressed in size (0.37 ± 0.24 mm² ) and showed clear follicle formation, whereas those without afferent lymphatic reconnection showed less size regression (1.31 ± 1.17 mm² ); the cell population was too dense to allow identification of follicles.

CONCLUSIONS

We established a mouse model of vascularized lymph node transfer with predictable afferent lymphatic reconnection. Both the vascularization and reconnection might be necessary for functional regeneration of the transferred lymph node.