This article has two goals. First, it reviews studies on tendinopathy in the literature while highlighting the following points: a) tendinopathy refers to a spectrum of tendon disorders with multiple facets of "tissue phenotypes," and b) mechanical loading is a major factor that contributes to the development of tendinopathy by inducing the aberrant differentiation of tendon stem/progenitor cells into non-tenocyte cell lineages. Second, the current treatments of tendinopathy with platelet-rich plasma (PRP) are briefly described, issues related to PRP treatment in clinics are highlighted, and the needs for basic science research on clinical usage of PRP for tendinopathy treatment are discussed.