Schema.org structure for a news aggregator individual post
HTML5+Microdata


In case of meta/link: 

If the value is a URI, you have to use link instead of meta. 

So this

&lt;meta itemprop="isBasedOnUrl" content="http://eluniverso.com/2015/03/01/noticia3.html" /&gt;


should be

&lt;link itemprop="isBasedOnUrl" href="http://eluniverso.com/2015/03/01/noticia3.html" /&gt;


and this

&lt;meta itemprop="logo" content="/logos/eluniverso.png" /&gt;


should be

&lt;link itemprop="logo" href="/logos/eluniverso.png" /&gt;

Your thumbnail img is missing the required alt attribute.


Schema.org


In addition to (or instead of) headline it can be beneficial to provide name. The headline property can only be used for CreativeWork (and sub-types), while the name property is defined for every type. It’s likely that many consumers look for and make use of name but not headline.

You could provide both properties, separated with a space, on the same element, i.e.,

&lt;h2 itemprop="headline name"&gt;

If the link in Organization is about this organization, you might want to use the url property.
The WebPage could reference the NewsArticle via the mainEntity property (if the page is only about a single news article; otherwise the NewsArticle could reference its WebPage with the reverse mainEntityOfPage property).

While you could use Microdata’s itemref attribute to reference it without changing the markup structure, it’s not necessary if markup changes are possible. You could specify WebPage on a container div (or the body, if it’s the only/current web page), e.g.:

&lt;div itemscope itemtype="http://schema.org/WebPage"&gt;

  &lt;!-- properties about the web page, i.e., the web page’s URL --&gt;

  &lt;article itemprop="mainEntity" itemscope itemtype="http://schema.org/NewsArticle"&gt;

    &lt;!-- properties about the news article, i.e., the news article’s URL --&gt;

  &lt;/article&gt;

  &lt;ul&gt;
    &lt;li&gt;&lt;a itemprop="relatedLink" href="/noticias/2015/02/01/original-breaking-news.html"&gt;Related News 1&lt;/a&gt;&lt;/li&gt;
    &lt;li&gt;&lt;a itemprop="relatedLink" href="/noticias/2015/02/02/more-data.html"&gt;Related News 2&lt;/a&gt;&lt;/li&gt;
    &lt;li&gt;&lt;a itemprop="relatedLink" href="/noticias/2015/02/03/other-thing-that-happened.html"&gt;Related News 3&lt;/a&gt;&lt;/li&gt;
  &lt;/ul&gt;

&lt;/div&gt;