M1 and M2 macrophage recruitment during tendon regeneration induced by amniotic epithelial cell allotransplantation in ovine

Abstract

Recently, we have demonstrated that ovine amniotic epithelial cells (oAECs) allotransplanted into experimentally induced tendon lesions are able to stimulate tissue regeneration also by reducing leukocyte infiltration. Amongst leukocytes, macrophages (Mφ) M1 and M2 phenotype cells are known to mediate inflammatory and repairing processes, respectively. In this research it was investigated if, during tendon regeneration induced by AECs allotransplantation, M1Mφ and M2Mφ phenotype cells are recruited and differently distributed within the lesion site. Ovine AECs treated and untreated (Ctr) tendons were explanted at 7, 14, and 28 days and tissue microarchitecture was analyzed together with the distribution and quantification of leukocytes (CD45 positive), Mφ (CD68 pan positive), and M1Mφ (CD86, and IL12b) and M2Mφ (CD206, YM1 and IL10) phenotype related markers. In oAEC transplanted tendons CD45 and CD68 positive cells were always reduced in the lesion site. At day 14, oAEC treated tendons began to recover their microarchitecture, contextually a reduction of M1Mφ markers, mainly distributed close to oAECs, and an increase of M2Mφ markers was evidenced. CD206 positive cells were distributed near the regenerating areas. At day 28 oAECs treated tendons acquired a healthy-like structure with a reduction of M2Mφ. Differently, Ctr tendons maintained a disorganized morphology throughout the experimental time and constantly showed high values of M1Mφ markers. These findings indicate that M2Mφ recruitment could be correlated to tendon regeneration induced by oAECs allotransplantation. Moreover, these results demonstrate oAECs immunomodulatory role also in vivo and support novel insights into their allogeneic use underlying the resolution of tendon fibrosis.

Therapeutic potential of hAECs for early Achilles tendon defect repair through regeneration

“…Altogether, these data strongly support the hypothesis that AECs provide therapeutic benefits during acute tendon healing (Barboni, Russo, et al, ; Mauro et al, ; Muttini et al, ; Muttini et al, ), thus reinforcing the clinical and preclinical evidences of their regenerative role through a direct use as native or amplified cells in regenerative medicine.…”

“…Moreover, the enhanced development of the inflammatory phase promoted by hAECs could represent another positive event leading to the early tendon healing that mimics what occurs when acute tendinopathies are promptly treated with anti‐inflammatory drugs (Richardson, Dudhia, Clegg, & Smith, ). First of all, as recently demonstrated in vivo for oAECs (Mauro et al, ), hAECs transplantation elicited a lower infiltration of leucocytes, T lymphocytes, and Mφ, thus confirming the in situ persistence of the inherited immunomodulatory activities demonstrated in vitro (Barboni, Russo, Curini, et al, ).…”

Human amnion favours tissue repair by inducing the M1-to-M2 switch and enhancing M2 macrophage features

“…The fact that hAMTCs and CM could switch the differentiation of pro‐inflammatory M1‐macrophages into a M2 anti‐inflammatory/immune‐suppressive phenotype could reveal the beneficial effects observed in different in vivo models (Parolini et al , ; Silini et al , ). Indeed, macrophage‐mediated resolution has been observed after treatment with amniotic‐derived cells or MSCs from different sources in liver fibrosis (Manuelpillai et al , ), multiple sclerosis (Liu et al , ), lung fibrosis (Murphy et al , ; Cargnoni et al , ; Tan et al , ), tendon lesions (Mauro et al , ) and skin wound healing (Zhang et al , ).…”

Tendon Biomimetic Electrospun PLGA Fleeces Induce an Early Epithelial-Mesenchymal Transition and Tenogenic Differentiation on Amniotic Epithelial Stem Cells

“…In a highly conserved manner, these types of extra-fetal stem cells express SSEA-3, SSEA-4, TRA-1-60, and TRA-1-81 embryonic markers and OCT4, SOX2, NANOG, and TERT pluripotent genes, which are responsible for their high plasticity [34]. AECs' immunomodulatory properties represent an important biological characteristic [35], as they can be successfully used in allo-and xeno-transplantation preclinical settings and clinical trials [32]. The natural inclination of AECs to undergo the Epithelial-Mesenchymal Transition (EMT) process [36] justifies their capacity to differentiate in vitro towards the mesenchymal lineage, as the tenogenic one, under adequate stimuli [33].…”