Abstract 120: Identification Of A Novel Adult Smooth Muscle-like Stem/progenitor Cell That Facilitates Formation Of Tissue Engineered Vascular Tissue For Use As Vascular Grafts In Vivo
The aim of this study was to characterise a recently identified adult smooth muscle stem-like/progenitor cell (SMSPC) and exploit the ability to differentiate contractile smooth muscle cells (SMC) from SMSPCs facilitating tissue engineering of small to medium arteries, an approach which is hampered by inadequate sources of, and scale up methodologies for autologous SMCs. We initially identified a novel SMSPC in the bone marrow (BM) of rats that retained classic stem cell-like characteristics (clonogenicity, unlimited self-renewal, high telomerase activity, expression of stem cell markers) whilst expressing low levels of SMC-like transcripts. Spontaneous differentiation favoured a SMC phenotype where ~20-fold increases in calponin and SM-MHC protein expression were observed 10 days post-embryoid body formation, an effect augmented by TGFβ (P < 0.0001). Differentiation of SMSPCs from an undifferentiated state towards contractile SMCs was Myocd-dependent. Overexpression of Myocd in SMSPCs increased their percentage contraction in response to AngII (P < 0.05) and KCL (P < 0.05) and Ca2+ signalling to levels indistinguishable from rat SMCs. Knockdown of SMC-specific repressors resulted in Myocd-dependent SMC differentiation of SMSPCs. Taking advantage of the fact that SMSPCs possessed unlimited self-renewal capacity ex vivo and could be successfully reprogrammed into functional SMCs, we determined the vascular tissue engineering potential of SMSPCs and showed these cells integrate as viable tissue engineered vascular grafts in vivo. Specifically, after 1 month implantation, a Myocd-GFP+/Isl1+ smooth muscle layer was observed in the grafts along with a vWF+ luminal endothelial layer and multi-layered collagen and elastin fibre formation throughout the graft wall. We have recently isolated cells with similar SMSPC phenotype and differentiation potential from human peripheral blood. This study demonstrates that adult SMSPCs derived from rat BM and human blood can be reprogrammed to efficiently generate large quantities of mature contractile SMCs, displaying great utility as a cellular backbone for tissue engineered vascular grafts, making them an attractive source for vascular cell therapy and surgical applications.
Evaluation of intra-tumoral (IT) SD-101 and pembrolizumab (Pb) in combination with paclitaxel (P) followed by AC in high-risk HER2-negative (HER2-) stage II/III breast cancer: Results from the I-SPY 2 trial.
508 Background: I-SPY 2 is a multicenter, phase 2 trial using response-adaptive randomization within molecular subtypes defined by receptor status and MammaPrint (MP) risk to evaluate novel agents as neoadjuvant therapy for women with high-risk breast cancer. SD-101 is an investigational Toll-like receptor 9 (TLR9) agonist CpG-C class oligodeoxynucleotide that stimulates the production of IFN-α and interleukin (IL)-12, functional maturation of plasmacytoid dendritic cells, and production of cytotoxic antibodies. IT SD-101 was combined with systemic anti-PD-1 antibody Pb to investigate the antitumor and immunologic activity of this novel immunotherapeutic strategy. Methods: Women with tumors ≥ 2.5cm were eligible for screening. Only pts (pts) with HER2- disease were eligible for this treatment. Treatment included weekly P x 12 in combination with IT SD-101 2 mg/ml (1 ml for T2 tumors, 2 ml for >T3 tumors) weekly x 4, then q3 weeks x 2, and IV Pb q3 weeks x 4, followed by doxorubicin/cyclophosphamide (AC) q2-3 weeks x 4 (SD-101+Pembro 4). Pts in the control arm received weekly P x 12 followed by AC q2-3 weeks x 4. The I-SPY 2 methods have been previously published. This investigational arm was eligible for graduation (>85% chance of success in a 300-person phase 3 neoadjuvant trial) in 3 of 10 pre-defined signatures: HER2-, hormone receptor (HR)+/HER2- and HR-/HER2-. Results: 75 pts were randomized and evaluable in SD-101+Pembro 4 treatment arm. The control arm included 329 historical controls enrolled since April 2010. The study arm was stopped due to maximal patient accrual. Pt characteristics were balanced; 56% HR+, 44% HR-. The probability that SD-101+Pembro4 was superior to control exceeded 97% for all eligible tumor signatures, but did not reach the threshold for graduation in any of the signatures. However, it is notable that the rate of pCR/Residual Cancer Burden 1 (RCB1) in the HR+/HER2- signature was 51%. Preliminary safety events for SD-101+Pembro 4 include increased rates of fever, neutropenia, febrile neutropenia, transaminitis, and immune-related events, including adrenal insufficiency. Conclusions: The SD-101+Pembro 4 regimen was active but did not meet the pre-specified threshold for graduation in I-SPY 2. pCR/RCB 1 analysis suggests improved response in the HR+/HER-negative signature compared to control. The clinical significance of these findings needs to be weighed against the potential risk of immune-related toxicities. Clinical trial information: NCT01042379. [Table: see text]
Behavioral Counseling Interventions for Healthy Weight and Weight Gain in Pregnancy