Comparison of NGS and MFC Methods: Key Metrics in Multiple Myeloma MRD Assessment.

In order to meet the challenges in data evaluation and comparability between studies in multiple myeloma (MM) minimal residual disease (MRD) assessment, the goal of the current study was to provide a step-by-step evaluation of next-generation sequencing (NGS) and multicolor flow cytometry (MFC) data. Bone marrow (BM) sample pairs from 125 MM patients were analyzed by NGS and MFC MM MRD methods. Tumor load (TL) and limit of detection (LOD) and quantification (LOQ) were calculated. The best-fit MRD cut-off was chosen as 1 × 10-5, resulting in an overall 9.6% (n overall = 12 (NGS n = 2, MFC n = 10)) nonassessable cases. The overall concordance rate between NGS and MFC was 68.0% (n = 85); discordant results were found in 22.4% (11.2% (n = 14) of cases in each direction. Overall, 55.1% (n = 60/109) and 49.5% (n = 54/109) of patients with a serological response ≥ very good partial response (VGPR) showed BM MRD negativity by NGS and MFC, respectively. A good correlation in the TL assessed by both techniques was found (correlation coefficient = 0.8, n = 40, p < 0.001). Overall, our study shows good concordance between MM BM MRD status and TL when comparing NGS and MFC at a threshold of 10-5. However, a sufficient number of analyzed events and calculation of MRD key metrics are essential for the comparison of methods and evaluability of data at a specific MRD cut-off.

Bone marrow-derived pancreatic stellate cells in rats.

Origin and fate of pancreatic stellate cells (PSCs) before, during and after pancreatic injury are a matter of debate. The crucial role of PSCs in the pathogenesis of pancreatic fibrosis is generally accepted. However, the turnover of the cells remains obscure. The present study addressed the issue of a potential bone marrow (BM) origin of PSCs. We used a model of stable hematopoietic chimerism by grafting enhanced green fluorescence protein (eGFP)-expressing BM cells after irradiation of acceptor rats. Chimerism was detected by FACS analysis of eGFP-positive cells in the peripheral blood. Dibutyltin dichloride (DBTC) was used to induce acute pancreatic inflammation with subsequent recovery over 4 weeks. Investigations have been focused on isolated cells to detect the resting PSC population. The incidence of eGFP-positive PSC obtained from the pancreas of chimeric rats was approximately 7% in healthy pancreatic tissue and increased significantly to a mean of 18% in the restored pancreas 4 weeks after DBTC-induced acute inflammation. Our results suggest that BM-derived progenitor cells represent a source of renewable stellate cells in the pancreas. Increased numbers of resting PSCs after regeneration point toward enhanced recruitment of BM-derived cells to the pancreas and/or re-acquisition of a quiescent state after inflammation-induced activation.

Preclinical analysis of treosulfan in combination with total body irradiation as conditioning regimen prior to bone marrow transplantation in rats.

Treosulfan (Treo) and total body irradiation (TBI) demonstrate a high therapeutic activity in treatment of acute leukemia and lymphoma. We investigated the combination of Treo and TBI prior to bone marrow transplantation (BMT) in rats. Female Lewis rats were treated with Treo on 3 consecutive days followed by TBI with either 5 Gy (n = 28) or 7.5 Gy (n = 48). After conditioning animals received 4 x 10E7 bone marrow cells (BC) from female Lewis rats. Additional 16 rats were transplanted with 4 x 10E7 BC and 1.5 x 10E7 spleen T-cells from female Brown-Norway (BN) rats. Animals were examined daily for clinical signs and toxicity was investigated by necropsy and histology in all animals. Gastrointestinal toxicity was the dose-limiting factor of Treo in combination with TBI. The highest tolerable dose of Treo in combination with 7.5 Gy TBI was 3 x 0.5 g/kg and the highest tolerable dose of Treo in combination with 5 Gy TBI was 3 x 0.6 g/kg. Allogeneic BMT from BN donors resulted in engraftment and survival of 12 out of 16 animals. Gastrointestinal toxicity is the dose-limiting factor in the treatment with Treo and TBI. Furthermore, Treo possesses certain characteristics of a radiosensitizer.