title: Presence of lymphatics in a rat tendon lesion model.
abstract: Tendons lack sufficient blood supply and represent a bradytroph tissue with prolonged healing time under pathological conditions. While the role of lymphatics in wound/defect healing in tissues with regular blood supply is well investigated, its involvement in tendon defects is not clear. We here try to identify the role of the lymphatic system in a tendon lesion model with morphological methods. A rat Achilles tendon lesion model (n = 5) was created via surgical intervention. Two weeks after surgery, animals were killed and lesioned site removed and prepared for polarization microscopy (picrosirius red) and immunohistochemistry using the lymphatic markers PROX1, VEGFR3, CCL21, LYVE-1, PDPN, and the vascular marker CD31. Additionally, DAPI was applied. Untreated tendons served as controls, confocal laser-scanning microscopy was used for documentation. At the lesion site, polarization microscopy revealed a structural reintegration while immunohistochemistry detected band-like profiles immunoreactive for PDPN, VEGFR3, CCL21, LYVE1, and CD31, surrounding DAPI-positive nuclei. PROX1-positive nuclei were detected within the lesion forming lines and opposed to each other. These PROX1-positive nuclei were surrounded by LYVE-1- or VEGFR3-positive surfaces. Few CD31-positive profiles contained PROX1-positive nuclei, while the majority of CD31-positive profiles lacked PROX1-positive nuclei. VEGFR3-, PDPN-, and LYVE-1-positive profiles were numerous within the lesion site, but absent in control tissue. Within 2 weeks, a structural rearrangement takes place in this lesion model, with dense lymphatic supply. The role of lymphatics in tendon wound healing is unclear, and proposed model represents a good possibility to study healing dynamics and lymphangiogenesis in a tissue almost completely lacking lymphatics in physiological conditions.
authors.affiliation: Institute of Tendon and Bone Regeneration, Paracelsus Medical University, Salzburg, Austria.
authors.forename: Herbert
authors.initials: H
authors.lastname: Tempfer
authors.forename: Alexandra
authors.initials: A
authors.lastname: Kaser-Eichberger
authors.forename: Stefanie
authors.initials: S
authors.lastname: Korntner
authors.forename: Christine
authors.initials: C
authors.lastname: Lehner
authors.forename: Nadja
authors.initials: N
authors.lastname: Kunkel
authors.forename: Andreas
authors.initials: A
authors.lastname: Traweger
authors.forename: Andrea
authors.initials: A
authors.lastname: Trost
authors.forename: Clemens
authors.initials: C
authors.lastname: Strohmaier
authors.forename: Barbara
authors.initials: B
authors.lastname: Bogner
authors.forename: Christian
authors.initials: C
authors.lastname: Runge
authors.forename: Daniela
authors.initials: D
authors.lastname: Bruckner
authors.forename: Karolina
authors.initials: K
authors.lastname: Krefft
authors.forename: Ludwig M
authors.initials: LM
authors.lastname: Heindl
authors.forename: Herbert A
authors.initials: HA
authors.lastname: Reitsamer
authors.forename: Falk
authors.initials: F
authors.lastname: Schrödl
mesh_terms: D000125:Achilles Tendon / Q000293:injuries / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D004195:Disease Models, Animal; D005260:Female; D007150:Immunohistochemistry; D042583:Lymphangiogenesis; D042601:Lymphatic Vessels / Q000378:metabolism / Q000473:pathology*; D018613:Microscopy, Confocal; D008859:Microscopy, Polarization; D011917:Rats, Inbred Lew; D013708:Tendon Injuries / Q000378:metabolism / Q000473:pathology*; D013997:Time Factors; D014945:Wound Healing
chemical_list: D015415:Biomarkers