Multimodal Optical Coherence Tomography for Intraoperative Evaluation of Tumor Margins and Surgical Margins in Breast-Conserving Surgery.

The aim of the study: We compare the effectiveness of multimodal optical coherence tomography (MM OCT) in the traditional structural OCT mode and the OCT elastography (OCE) mode in addressing two clinically important tasks: (1) detecting groups of tumor cells at surgical margins during breast-сonserving surgery (BСS) in breast cancer (BC) and (2) identifying breast tumor margins. The obtained results were correlated with corresponding histological sections. Materials and Methods: The study was performed on 100 surgical margin samples (top, bottom, medial, and lateral - four samples from each patient in total) obtained from 25 patients with BC who underwent BCS (lumpectomy), and on 25 postoperative tumor samples (to determine tumor margins). With MM OCT method, we visually and numerically assessed the scattering (level and depth of OCT signal penetration) and elastic (stiffness values, or Young's modulus (kPa)) properties of the tumor and non-tumor breast tissue and the obtained values were compared with the results of postoperative histological examination. Results: In 4 surgical margin samples (out of 100), with the OCE method we identified groups of histologically confirmed tumor cells ("positive" resection margins) at the distance of about 5 mm from the visible tumor margin. The identified zones were larger than 0.5 mm with stiffness of more than 400 kPa in all these cases. However, the structural OCT could not identify these groups of tumors and they were not distinguishable from the surrounding fibrous tissue.In the areas of tumor into non-tumor tissue transition, structural OCT images detected tumor margins only if they were adjacent to adipose tissue and did not detect them if there were adjacent to non-tumor fibrous tissue. OCE images with high stiffness values (more than 400 kPa) and high contrast showed a clear tumor margin with both adipose and fibrous tissue. Conclusion: The study demonstarets the potential of MM OCT, particularly its OCE mode, as a real-time method for intraoperative tumor margin and surgical margin assessment in BCS. OCE images compared to structural OCT images visualize higher contrast between different types of breast tissue (adipose tissue, fibrous stroma, hyalinized stroma, tumor cell clusters), as well as more accurate identification of the tumor border and detection of small groups of tumor cells at surgical margins. An algorithm for intraoperative MM OCT examination of the state of the resection margin is proposed in accordance with standard clinical guidelines for achieving clean surgical margins in breast cancer patients.

[Culture of human amniotic fluid stem cells in 3D collagen matrix].

Most of the researchers attribute amniotic fluid stem cells (AF SCs) to mesenchymal stem cells (MSCs). However, AF SCs express both mesenchymal and epithelial markers, which distinguishes them from postnatal MSCs. Cultivation in the three-dimensional matrix provides a different look at the nature of these cells. We showed that, in 3D collagen gel, AF SCs form epithelial structures (tubules and cysts). Active contraction of the gel during the first days of cultivation, which is characteristic if mesenchymal cells, does not occur. Electron microscopic study showed that typical to epithelial cell adherent junctions are formed between AF SCs. On the other hand, AF SCs continue to express MSCs markers during cultivation in the gel. Thus, AF SCs may not be true mesenchymal cells because they can display properties of epithelial cells. Perhaps these cells undergo epithelial-mesenchymal transition, the process which actively takes place during embryogenesis.

[Stem cells in human amniotic fluid].

Amniotic fluid (AF) contains a heterogeneous population of cells of fetal origin in which stem cells are present. These cells are characterized by their expression of mesenchymal (CD73, CD90, CD105) and neural (Nestin, @[beta]3-tubulin, NEFH) markers, and also some pluripotent markers (Oct4, Nanog), and they are capable of differentiating into diverse derivatives in vitro. We have shown that epithelial markers are observed in AF stem cells at the same time with mesenchymal (Keratin 19, Keratin 18, and p63). During cloning, colonies of cells with fibroblastlike and epithelial-like morphologies are formed. The status and differentiation potential of stem cells from AF have been discussed.

Cell phenotypes in human amniotic fluid.

Stem cells capable of long-term proliferation and differentiation into different cell types may be a promising source of cells for regenerative medicine. Recently, much attention has been paid to fetal stem cells, among which are cells from amniotic fluid (AF). We have isolated amniotic stem cells from 3 AF samples. Flow cytometry, RT -PCR and immunohistochemistry have shown that these cells express mesenchymal (CD90, CD73, CD105, CD13, CD29, CD44, and CD146), neural (≤3-tubulin, Nestin, and Pax6), epithelial (keratin 19 and p63) markers and also markers of pluripotency (Oct4, Nanog, and Rex-1). Transplantation of the cells to nude mice does not lead to tumor formation. Thus, putative stem/progenitor cells from AF are capable of long-term proliferation in vitro and the profile of gene expression led us to speculate that they have greater differentiation potential than mesenchymal stem cells and may be useful for cell therapy.