// responses is an ObservableCollection where I add the content from http responses
responses.Add(content);
// dataGrid.ItemsSource is binded to responses
dataGrid.ScrollIntoView(content);

((INotifyCollectionChanged)DataGrid.Items).CollectionChang‌​ed += CollectionChangedEventHandler;

private void CollectionChangedEventHandler(object sender, NotifyCollectionChangedEventArgs e)
{
    var itemCollection = sender as ItemCollection;

    // How to access ModelParent here?
}

var dataGrid = itemCollection.GetType().GetProperty("ModelParent").GetValue(itemCollection);