A novel pilot animal model for the surgical prevention of lymphedema: the power of optical imaging

Prophylactic Lymphaticovenous Anastomosis Performed with Lymphadenectomy is Oncologically Safe for Melanoma

BACKGROUND

A major concern of lymphaticovenous anastomosis (LVA), which has not been studied, is increased risk of metastasis. Melanoma patients with macrometastatic lymph node disease represent a high-risk group for recurrence and metastasis. On the basis of a literature review, this present study is the first to evaluate the impact of prophylactic LVA on cancer survival and recurrence.

METHODS

This was a comparison study of patients with cutaneous melanoma who underwent therapeutic lymphadenectomy alone (comparison group) or combined with prophylactic LVA (LVA group) between 2014 and 2020. A single surgeon performed all cancer resections, therapeutic lymphadenectomies, and LVA. Exclusion criteria included non-melanoma skin cancers, stage IV cancers before lymphadenectomy, microscopic lymphatic disease (i.e., positive sentinel node biopsy was the sole indication for lymph node dissection), or follow-up time less than 12 months unless the patient died earlier owing to melanoma-related complications.

RESULTS

This study included 23 patients in the LVA group and 22 consecutive patients in the comparison group. The two groups were similar in age, sex, and cancer stages. The comparison group had longer follow-up times (median 67.62 versus 29.73 months in the LVA group; p < 0.01). Average size of largest metastatic lymph node was 45.91 ± 35.03 mm and 44.54 ± 23.32 mm in the LVA and comparison groups, respectively (p = 0.99). There were no differences in OS, DMFS, and RFS times after more than 2 years of follow-up since the index surgery.

CONCLUSION

Prophylactic LVA performed for macrometastatic melanoma is not a strong risk factor for relapse and metastasis.

LEVEL OF EVIDENCE

II Therapeutic.

Acquired lymphedema: Molecular contributors and future directions for developing intervention strategies

Lymphedema is a debilitating chronic disease that mostly develops as an adverse reaction to cancer treatment modalities such as chemotherapy, surgery, and radiotherapy. Lymphedema also appears to be a deteriorating consequence of roundworm infections, as best represented by filariasis. According to its origin, lymphedema is classified as primary lymphedema and acquired lymphedema. The latter is an acquired condition that, hitherto, received a considerably low attention owing to the less number of fatal cases been reported. Notably, despite the low mortality rate in lymphedema, it has been widely reported to reduce the disease-free survival and thus the quality of life of affected patients. Hence, in this review, we focused on acquired lymphedema and orchestration of molecular interplays associated with either stimulation or inhibition of lymphedema development that were, in vast majority, clearly depicted in animal models with their specific and distinct technical approaches. We also discussed some recent progress made in phytochemical-based anti-lymphedema intervention strategies and the specific mechanisms underlying their anti-lymphedema properties. This review is crucial to understand not only the comprehensive aspects of the disease but also the future directions of the intervention strategies that can address the quality of life of affected patients rather than alleviating apparent symptoms only.

Novel Quantification of Real-Time Lymphatic Clearance: Immediate Lymphatic Reconstruction in a Large-Animal Model

BACKGROUND

The real-time quantification of lymphatic flow remains elusive. Efforts to provide a metric of direct lymphatic function are not clinically translatable and lack reproducibility. Early reports demonstrate the promise of immediate lymphatic reconstruction (immediate lymphovenous bypass after lymphadenectomy) to reduce the risk of lymphedema development. However, there remains a heightened need to appraise this technique in a clinically translatable large-animal model. The aim of the authors' experiment was to evaluate the role of molecular imaging in the quantification of real-time lymphatic flow after lymphadenectomy, and lymphadenectomy with lymphovenous bypass using novel fluorophores in a swine model.

METHODS

A lymphadenectomy or lymphadenectomy with subsequent lymphovenous bypass was performed in 10 female swine. After subdermal fluorophore injection, near-infrared molecular imaging of blood samples was used to evaluate change in lymphatic flow after lymphadenectomy versus after lymphadenectomy with lymphovenous bypass. Continuous imaging evaluating fluorescence of the superficial epigastric vein in the torso and adjacent skin was performed throughout all experiments. Findings between modalities were correlated.

RESULTS

The near-infrared dye signal in central and peripheral blood samples was often difficult to separate from background and proved challenging for reliable quantification. Venous and skin near-infrared imaging demonstrated a lymphatic clearance rate decrease of 70 percent after lymphadenectomy versus a decrease by only 30 percent after lymphadenectomy with immediate lymphovenous bypass.

CONCLUSIONS

In this article, the authors describe a noninvasive, swine, large-animal model to quantify lymphatic clearance using skin imaging. The authors' findings were consistent with results yielded from real-time imaging of the vein. The authors believe this model may have important implications for eventual direct translation to the clinical setting.

Enhancement of Lymphatic Vessels in the Superficial Layer in a Rat Model of a Lymphedematous Response

Background:

The morphologic and histologic behavior of lymphatic vessels in lymphedema has not been well analyzed using laboratory animals. The purpose of the present study was to elucidate the regeneration process of lymphatic vessels after acute lymphedema in a rat model.

Methods:

The acute lymphedema was induced by an amputation and a replantation surgery on a rat hind limb. Recovery of lymphatic flow was traced using fluorescent lymphography with dye injection. The morphology and number of lymphatic vessels were immunohistochemically detected and quantified in both superficial and deep layers.

Results:

The swelling was the most severe, and the number of lymphatic vessels in the superficial layer was significantly and maximally increased on postoperative day 3. Backflows and overflows were also detectable in the superficial layer on postoperative day 3. The number of lymphatic vessels had decreased but remained significantly higher than that in the controls on postoperative day 14, when the swelling decreased to the levels in the controls. In contrast, the number of lymphatic vessels in the deep layer showed a tendency toward increased numbers; however, it was not statistically significant on postoperative day 3, 7, or 14.

Conclusions:

We have obtained solid evidence showing the differential potency of lymphatic vessels between the superficial and the deep layers after temporal lymphedematous induction. Further analysis of lymphedematous responses in animal models could provide new insights into the challenges associated with the clinical treatment of lymphedema.