15d-PGJ₂ enhances platelet production from megakaryoblast cell lines. (A) Meg-01, M07e, or Dami cells (10⁶) were treated with 15d-PGJ₂ (10 μM) for 24 hours. 15d-PGJ₂ increases platelet production in Meg-01, M07e, and Dami cells after 24 hours. (B) Meg-01 (10⁶) cells were treated with prostaglandins for 24 hours. 15d-PGJ₂ dose-dependently increased platelet production in Meg-01 cells after 24 hours, unlike PGE₂ (10 μM), PGI₂ (10 μM), and PGF_2α (10 μM). (C) 92% of the Meg-01–derived platelets expressed the platelet surface marker CD61. Isotype control is shown by the left histogram. Results are presented as mean plus or minus SD (P < .05). (D) Forward and side scatter plots showing that platelets produced from untreated and 15d-PGJ₂–treated (10 μM for 24 hours). Meg-01 cells mimic freshly isolated human platelets in their ability to undergo shape change with 15 minutes of collagen treatment (10 μg/mL). Eighty-seven percent of human platelets, 87% of Meg-01–derived platelets, and 68% of the platelets produced from 15d-PGJ₂–treated Meg-01 cells decreased their size (forward scatter) and increased their granularity (side scatter) in response to collagen. (E) Histogram plots showing that Meg-01–derived platelets are similar to normal human platelets in their ability to undergo annexin V binding in both the presence and absence of collagen. Values are geometric mean fluorescence intensity. (F) Meg-01 cells were untreated or treated with DMSO (vehicle) or 15d-PGJ₂ (10 μM) for 2 hours. Phalloidin staining of f-actin fibers shown by fluorescence microscopy in an untreated cell. Note DAPI-stained nucleus (n) and smooth rounded cell surface. (G) Phalloidin staining of f-actin fibers shown by fluorescence microscopy. Left picture shows heavy phalloidin staining of organized f-actin bundles in a cell treated with 10 μM of 15d-PGJ₂ for 2 hours. Right picture shows enlarged (×40) section highlighting membrane demarcations. Arrows show heavy phalloidin staining of f-actin bundles. (H) Meg-01 cells were untreated or treated with 10 μM of 15d-PGJ₂ for 24 hours. Transmission electron microscopy (TEM) shows an untreated cell; note smooth round nucleus (n) and the absence of granules. (I) Left TEM picture shows a cell treated with 10 μM of 15d-PGJ₂ for 24 hours. Note horseshoe-shaped nucleus (n), granule content (g), and cytoplasmic extensions (c). Right picture shows enlarged section highlighting cytoplasmic extensions.