 Shares of Establishment Labs Holdings Inc. ESTA, -1.50 tumbled 21.7 toward a 21-month low in premarket trading Wednesday, after short-seller Hindenburg Research took aim at the silicone breast implant company. Hindenburg alleged that it found most safety studies of the companys products have conflicts of interest, and that many patient testimonials and multiple lawsuits dispute the companys claims of safety and satisfaction. 