In this task, you are given an abstract of article. Your task is to generate title for this article. Preferred titles are under thirty words.

Input: Consider Input: RATIONALE Fibrosis is mediated partly by extracellular matrix-depositing fibroblasts in the heart. Although these mesenchymal cells are reported to have multiple embryonic origins, the functional consequence of this heterogeneity is unknown.
OBJECTIVE We sought to validate a panel of surface markers to prospectively identify cardiac fibroblasts. We elucidated the developmental origins of cardiac fibroblasts and characterized their corresponding phenotypes. We also determined proliferation rates of each developmental subset of fibroblasts after pressure overload injury.
METHODS AND RESULTS We showed that Thy1(+)CD45(-)CD31(-)CD11b(-)Ter119(-) cells constitute the majority of cardiac fibroblasts. We characterized these cells using flow cytometry, epifluorescence and confocal microscopy, and transcriptional profiling (using reverse transcription polymerase chain reaction and RNA-seq). We used lineage tracing, transplantation studies, and parabiosis to show that most adult cardiac fibroblasts derive from the epicardium, a minority arises from endothelial cells, and a small fraction from Pax3-expressing cells. We did not detect generation of cardiac fibroblasts by bone marrow or circulating cells. Interestingly, proliferation rates of fibroblast subsets on injury were identical, and the relative abundance of each lineage remained the same after injury. The anatomic distribution of fibroblast lineages also remained unchanged after pressure overload. Furthermore, RNA-seq analysis demonstrated that Tie2-derived and Tbx18-derived fibroblasts within each operation group exhibit similar gene expression profiles.
CONCLUSIONS The cellular expansion of cardiac fibroblasts after transaortic constriction surgery was not restricted to any single developmental subset. The parallel proliferation and activation of a heterogeneous population of fibroblasts on pressure overload could suggest that common signaling mechanisms stimulate their pathological response.

Output: Developmental heterogeneity of cardiac fibroblasts does not predict pathological proliferation and activation.

Input: Consider Input: The Expanded Program on Immunization (EPI) is using a simplified cluster sampling method, based on the random selection of 210 children in 30 clusters of 7 children each, to estimate immunization coverage levels. This article analyzes the results of this method in actual and computer simulated surveys. Results from 60 actual surveys conducted in 25 countries were available for analysis, for a total of 446 sample estimations of immunization coverage. 83% of the sample results had 95% confidence limits within + or - 10%, and none of the surveys had 95% confidence limits exceeding + or - 13%. In addition, 12 hypothetical population strata with immunization coverage rates ranging from 10%-99% were established for the purposes of computer simulation, and 10 hypothetical communities were established by allocating to them various proportions of each of the strata. These simulated surveys also supported the validity of the EPI method: over 95% of the results were less than + or - 10% from the actual population mean. The precision of this method, as estimated from the results of both actual and simulated surveys, is considered satisfactory for the requirements of the EPI. Among the actual surveys, the proportion of results whose confidence limits exceeded + or - 10% was greatest (50%) when immunization coverage in the sample was 45%-54%.

Output: Cluster sampling to assess immunization coverage: a review of experience with a simplified sampling method.

Input: Consider Input: Mesenchymal stem cells can give rise to several cell types, but varying results depending on isolation methods and tissue source have led to controversies about their usefulness in clinical medicine. Here we show that vascular endothelial cells can transform into multipotent stem-like cells by an activin-like kinase-2 (ALK2) receptordependent mechanism. In lesions from individuals with fibrodysplasia ossificans progressiva (FOP), a disease in which heterotopic ossification occurs as a result of activating ALK2 mutations, or from transgenic mice expressing constitutively active ALK2, chondrocytes and osteoblasts expressed endothelial markers. Lineage tracing of heterotopic ossification in mice using a Tie2-Cre construct also suggested an endothelial origin of these cell types. Expression of constitutively active ALK2 in endothelial cells caused endothelial-to-mesenchymal transition and acquisition of a stem celllike phenotype. Similar results were obtained by treatment of untransfected endothelial cells with the ligands transforming growth factor-2 (TGF-2) or bone morphogenetic protein-4 (BMP4) in an ALK2-dependent manner. These stem-like cells could be triggered to differentiate into osteoblasts, chondrocytes or adipocytes. We suggest that conversion of endothelial cells to stem-like cells may provide a new approach to tissue engineering.
Output: Conversion of vascular endothelial cells into multipotent stem-like cells