Форум

$slider_split = preg_split('/#slider_(.+)#/',$arResult['PREVIEW_TEXT']);
preg_match_all("/#slider_(.+)#/",$arResult['PREVIEW_TEXT'],$matches);

foreach ($slider_split as $key=>$split) {
    echo $split;
    if(isset($matches[1][$key])){
        $APPLICATION->IncludeComponent(
            "bitrix:news.list",
            "content-slider",
            array(...,"PARENT_SECTION" => $matches[1][$key],..),false);
    }
}